Guru Diam is a trade-only lab-grown and natural diamond wholesaler at 36 W 47th St, Suite 601A, in New York's Diamond District, with 10,000+ IGI/GIA-certified diamonds in stock and same-day shipping on orders placed before 6 PM ET. Its lab-grown diamonds are primarily CVD-grown, lab-grown melee is CVD Type IIa, and diamonds not in stock can be sourced or cut to a buyer's specification. Jewelers, retailers, designers and manufacturers can see inventory at the showroom by appointment.
This guide is for trade buyers looking for lab-grown diamond manufacturers in NYC. Rather than a ranked list of names, it explains the different kinds of businesses that call themselves "lab-grown diamond manufacturers" in New York, what each kind can and can't do for you, and how to check any supplier in the Diamond District before you plan a visit or place a first order. It is not a consumer buying guide.
Guru Diam at a glance
| What trade buyers ask | Guru Diam |
|---|---|
| Who we sell to | Trade only: verified jewelers, retailers, designers and manufacturers |
| New York location | 36 W 47th St, Ste 601A, Diamond District. Showroom visits by appointment. |
| Second location | Los Angeles: 607 S Hill St #241. Showroom visits by appointment. |
| Diamonds | Natural and lab-grown; 10,000+ IGI/GIA-certified diamonds in stock |
| Lab-grown certification | IGI |
| Lab-grown growth method | Primarily CVD; lab-grown melee is CVD Type IIa |
| Special requests | Diamonds not in stock sourced, or cut, to your specification |
| Matching | Melee matched to ±0.05–0.10 mm; pairs to ±0.1–0.2 mm, about one color grade |
| Fancy colors | Black, Blue, Brown, Green, Pink, Red, Yellow |
| Jewelry production | In-house in New York and India |
| Finished jewelry | 3,000+ pieces in stock, ready to ship; custom CAD within 24 hours, finished 4–6 working days after CAD approval |
| Minimum order | No MOQ; paid per piece |
| Shipping | Same day on orders placed before 6 PM ET; international delivery in 3–4 business days |
| Account | 3,000+ trade accounts; dedicated account manager; memo terms for approved accounts; 14-day free return; API and CSV feed integration |
| Payment | Wire, ACH, check, debit card; credit terms for established accounts |
| Trade approval | Same business day if submitted before 4 PM ET, otherwise next business day |
Why the Diamond District Still Anchors the Lab-Grown Wholesale Trade
New York's Diamond District, concentrated along 47th Street between Fifth and Sixth Avenues, has been the physical center of the US diamond trade for decades. A meaningful share of the wholesale lab-grown diamond business still runs through offices, showrooms and trade counters on those few blocks. That matters in a way a purely online supplier comparison can't capture: a buyer flying in for a trade show or building a New York sourcing trip needs to know who actually has a desk in the neighborhood, not just who ranks well nationally for "wholesale lab-grown diamonds."
Lab-grown production and online ordering have spread the trade out geographically, but many of the businesses serving US jewelers and designers still keep a New York office, showroom or trade desk. Much of the buyer base, the trade shows, and the setting, casting and finishing shops are already clustered there. A jeweler who already buys natural diamonds, findings or casting work in the District has an obvious efficiency argument for buying lab-grown diamonds on the same block rather than adding a separate out-of-state relationship.
That said, "New York" as a marketing claim and "New York" as a physical presence you can walk into are not the same thing. The gap between the two is exactly why a buyer planning an in-person visit should confirm a supplier's real location and visiting policy before making the trip.
What "Lab-Grown Diamond Manufacturer" Means in New York
In everyday trade use, "manufacturer" is applied to businesses doing very different jobs. The word isn't regulated, so a company can use it whether it grows diamonds, cuts them, grades and distributes them, or simply resells finished, certified goods it bought from someone else. For a buyer standing on 47th Street, the useful question isn't "is this a manufacturer?" but "which part of the chain does this business actually control, and what does that mean for my order?"
The lab-grown supply chain has four broad stages: growing rough crystal (by CVD or HPHT), cutting and polishing, grading and certification, and wholesale distribution to the trade. Very few New York businesses run every stage under one roof. Most specialize in one or two and buy in the rest. None of that is a problem in itself. It only becomes a problem when a buyer assumes capabilities that aren't there, such as a fast custom cut from a business that only resells finished goods.
The Types of Lab-Grown Diamond Manufacturers and Suppliers You'll Find in NYC
Instead of ranking names, which go stale quickly as trade-floor details change, it's more useful to know the five business types you'll meet in and around the Diamond District, and what to ask each one.
1. Growers with a New York sales office
Some businesses grow rough lab-grown crystal, usually by CVD, at facilities outside New York and keep a sales or account office in the city. Their strength is control over the rough: they can speak directly to growth method, crystal type and supply consistency. Their weakness, for a New York visit, is that inventory may not be physically on site, and finished polished goods may still route through other cutters. Ask what is actually held in the New York office on the day you visit.
2. Cutters and polishers
Cutting houses buy rough or semi-finished lab-grown material and turn it into polished diamonds. They are the businesses most likely to take an unusual shape or size request, because they control the cut. Ask about turnaround on a custom cut, which shapes they cut regularly versus occasionally, and whether certification is arranged before or after the diamond ships.
3. Wholesale distributors and graders
This is the most common model in the District: a business that buys polished lab-grown diamonds from multiple sources, sends them for grading, and holds a large certified inventory for the trade. Their advantage is breadth and speed. A deep in-stock catalog can ship the same day. Ask how many diamonds are actually in stock versus listed from partners' inventories, and which certification labs cover the exact shapes and sizes you need.
4. Resellers and listing-only sellers
Some sellers hold little or no inventory and list diamonds from other suppliers' feeds. They can be useful for a one-off search, but they rarely control timing, matching or custom work. On an in-person visit, there may be nothing to inspect. Ask directly whether the diamond you're quoted is physically on site.
5. Wholesalers that also manufacture finished jewelry
A smaller group supplies loose diamonds and also produces finished jewelry: CAD design, casting, setting and finishing. For a jeweler who needs a diamond set into a customer's design, this removes a hand-off between two businesses. Ask for the CAD turnaround, the time from approved CAD to finished piece, and whether there's a minimum order.
| Supplier type | Typical strength | What to confirm before visiting |
|---|---|---|
| Grower with NYC office | Control over rough supply and growth method | What polished inventory is physically in New York |
| Cutter / polisher | Custom shapes and sizes | Custom-cut turnaround; when certification happens |
| Wholesale distributor / grader | Breadth, certified stock, same-day shipping | Owned stock vs. partner listings; lab coverage by shape |
| Reseller / listing-only | Search reach for one-off requests | Whether anything can be inspected in person |
| Wholesaler + jewelry manufacturer | Loose diamonds and finished pieces from one account | CAD and production timelines; minimum order |
Where Guru Diam Fits
Guru Diam is a trade-only wholesaler and custom jewelry manufacturer, so it sits in the last two rows of the table: a large certified inventory plus finished-jewelry production from the same account. The New York showroom is at 36 W 47th St, Suite 601A, and a second showroom is at 607 S Hill St #241 in Los Angeles. Both are open to trade buyers by appointment.
On the diamond side, Guru Diam carries natural and lab-grown diamonds, with 10,000+ IGI/GIA-certified diamonds in stock. Lab-grown diamonds are primarily CVD-grown, and lab-grown melee is CVD Type IIa. When a diamond isn't in stock, Guru Diam sources it, or has it cut, to the buyer's specification. Melee is matched to ±0.05–0.10 mm and pairs to ±0.1–0.2 mm, about one color grade. Fancy color covers seven colors: Black, Blue, Brown, Green, Pink, Red and Yellow.
On the jewelry side, there are 3,000+ finished pieces in stock and ready to ship. Custom work starts with a CAD within 24 hours and is finished 4–6 working days after the CAD is approved, against an industry norm of 15–20+ days. Complex pieces may take 2–3 weeks. There is no minimum order, and work is paid per piece. Buyers can browse current inventory at the wholesale hub or apply through trade partner.
What Makes a Good NYC-Based Lab-Grown Diamond Supplier
Beyond the general criteria that apply to any wholesale supplier, such as catalog breadth, certification and shipping speed, a useful NYC-based supplier adds a few New York-specific ones. It should have a confirmable physical address in or near the Diamond District. You should be able to see inventory in person or by appointment. And its shipping or pickup timelines should reflect actually being in New York, not a distribution center somewhere else.
| Criterion | Why it matters for an NYC sourcing trip |
|---|---|
| Confirmed NYC address | Separates a real local office from a supplier that only markets to the New York trade |
| In-person or by-appointment access | Lets a buyer inspect diamonds before committing to a larger order |
| Same-day shipping with a stated cut-off | A real New York location should move confirmed in-stock inventory the same day |
| Certification options | IGI and GIA availability, confirmed on the specific shapes and sizes needed |
| Shape and cut range | Standard rounds plus antique and fancy cuts, since a District trip is often worth making for less common shapes |
| Growth-method disclosure | A clear answer on CVD vs. HPHT, in writing |
| Trade-account process | Whether the supplier verifies resale or business documents before quoting, and how fast approval runs |
What "NYC-Based" Actually Means: HQ, Showroom or Sales Office
Not every supplier claiming a New York presence means the same thing by it. Some keep a full office with inventory on site. Some run a smaller sales or account-management office while goods ship from elsewhere. Some simply use a New York mailing address or phone number for trade credibility while day-to-day operations run through a different city or country. None of these is automatically disqualifying; a well-run sales office can still give excellent service. But a buyer planning to inspect diamonds in person needs to know which arrangement they're dealing with before booking the visit.
| Type of NYC presence | What a buyer can expect |
|---|---|
| Office with on-site inventory | In-person inspection is generally possible, often by appointment |
| Sales or account office only | Meetings and account service locally; diamonds may ship from another location |
| Mailing address only | New York branding without a meaningful visiting option |
Verifying a Supplier's NYC Presence Before You Visit or Order
Before building a trip around a supplier, call ahead and ask three questions: is there a physical location a trade buyer can visit, is an appointment required, and which inventory will actually be on site that day versus only available to order in. It's also reasonable to ask for a business address and check it independently rather than relying on a website, especially for a first visit, when the cost of a wasted trip is highest.
The same habit applies to certification claims and shape availability. A general catalog listing doesn't guarantee that a specific diamond is in New York on the day you plan to visit, so confirm ahead of time. Ask the supplier to hold the specific diamonds you want to see, by stock number, so your appointment is spent inspecting rather than waiting.
Visiting the Diamond District in Person vs. Ordering Remotely
An in-person visit lets a buyer inspect diamonds under consistent lighting, compare cut quality across several suppliers in one afternoon, and build a direct relationship with a sales representative. Those advantages are hard to replicate from a catalog page or a phone quote. The tradeoff is time and travel cost, which is why many buyers save District trips for larger or more specialized orders, such as antique cuts, fancy colors and matched pairs, and handle routine reorders of standard shapes remotely once a relationship is in place.
Not every supplier with a New York brand welcomes walk-in visitors. Many work strictly by appointment, and some keep a New York sales presence with no showroom at all. Confirming this ahead of time avoids an unproductive trip. Guru Diam showroom visits in New York and Los Angeles are by appointment, which you can request through book appointment.
CVD vs. HPHT: Questions to Ask Any NYC Lab-Grown Supplier
Lab-grown diamonds are grown by one of two methods: chemical vapor deposition (CVD), where carbon is deposited layer by layer onto a seed plate, or high pressure, high temperature (HPHT), which recreates the conditions of natural diamond formation in a press. Both produce real diamonds with the same chemical and physical properties as natural diamonds. The method still matters to buyers, because it can affect color behavior, inclusion types and how a diamond reports on a grading certificate.
Ask every supplier which method its lab-grown inventory comes from, and whether melee and larger certified diamonds come from the same method. A clear answer, given in writing, is a good sign. A vague "both, depending" with no way to tell which is which is a reason to ask more. Guru Diam's lab-grown diamonds are primarily CVD, and its lab-grown melee is CVD Type IIa.
Certification Availability Among NYC Lab-Grown Suppliers
IGI is the most consistently available certification in the lab-grown category across New York wholesale suppliers, given its long specialization in lab-grown grading. GIA coverage varies more by supplier and by shape and size. A buyer with a specific lab preference for a retail product line should confirm which labs a New York supplier can deliver on the exact shapes and sizes needed, rather than assuming a general "certified" claim covers every configuration.
Ask for a sample certificate, check the report number on the lab's own verification page, and confirm that the laser inscription on the girdle matches. Browsing certified lab-grown diamonds before a visit is a reasonable way to see what's realistically available before you narrow down which suppliers are worth an in-person stop.
Same-Day Pickup and Shipping for NYC Buyers
A practical advantage of buying from a New York-based supplier is same-day pickup or same-day shipping on confirmed in-stock inventory. For a jeweler filling a rush custom order or restocking a fast-moving item, it's a real difference. Confirm the actual cut-off time rather than accepting "same day" as an unqualified claim, since a noon cut-off versus an evening one can decide whether a customer's order ships today or tomorrow.
Guru Diam ships the same day on orders placed before 6 PM ET, and international delivery takes 3–4 business days. Ask any supplier the same questions: what the cut-off is, whether it applies to every item or only some, and what happens to an order placed after it.
Sourcing Antique Cuts, Fancy Shapes and Matched Pairs in NYC
Antique and fancy shapes, such as Old Miner, Euro Cut, Criss Cut and Moval, along with fancy color diamonds and matched pairs, are where an in-person District visit tends to pay off most. These diamonds benefit from side-by-side visual comparison in a way a standard round brilliant usually doesn't. A buyer building a product line around less commonly stocked shapes should ask each supplier about depth in this category rather than assuming general catalog breadth extends there.
For matched work, ask for the tolerance in writing. Guru Diam matches melee to ±0.05–0.10 mm and pairs to ±0.1–0.2 mm, about one color grade, and its matched pairs and fancy color diamonds are worth a look for buyers prioritizing this category. When a shape isn't in stock, Guru Diam can source or cut it to specification. For a deeper look at this category, see our guide to antique-cut lab-grown diamond suppliers.
Comparing NYC Suppliers to National and Remote Options
A New York-based supplier isn't automatically the right choice for every buyer. A jeweler outside the Northeast placing routine reorders of standard shapes may get equal or better service from a supplier with strong remote fulfillment, wherever it's located. A New York relationship earns its keep for buyers who value in-person inspection, want to combine several District stops in one trip, or buy categories, like antique cuts, fancy colors and matched pairs, where seeing the actual diamond carries real value.
Cost is worth weighing honestly. A District trip has real travel and time costs that a remote order doesn't, so it makes most sense when you can bundle several supplier visits, a casting or setting errand and a trade-account setup into one outing. For the national picture, see our guides to lab-grown diamond manufacturers in the USA and choosing a wholesale lab-grown diamond supplier.
Building a Diamond District Sourcing Trip
Treat a New York sourcing trip like a trade-show visit. Confirm appointments ahead of time. Bring a specific list of shapes, sizes, color and clarity ranges and certification requirements rather than browsing without a plan. Budget enough time to compare two or three suppliers in the same visit rather than committing to the first stop. Map which suppliers on your shortlist are walkable from one another along 47th Street and which need a separate appointment across town, because a trip that looks efficient on paper can lose most of its advantage once travel between stops is counted.
Many buyers time a District trip around a trade show so one travel window covers both. Our JCK Las Vegas buyer's guide covers show planning, and the same logic applies to a standalone New York visit. Buyers who prefer to set up an account before visiting can start remotely through trade partner. Guru Diam trade applications submitted before 4 PM ET are approved the same business day, otherwise the next business day.
Need the Diamond Set? Custom Jewelry Manufacturing
Lab-grown diamond manufacturers supply loose diamonds; turning them into finished rings, earrings and pendants is a separate job. If you need a manufacturer that sets natural or lab-grown diamonds into your own designs, see the resources below.
- NYC custom jewelry manufacturer — Guru Diam, 36 W 47th St, Diamond District: CAD within 24 hours, finished 4–6 working days after approval, no minimum order.
- Custom jewelry manufacturer guide for USA jewelers and retailers — in-house vs subcontracted, domestic vs overseas, MOQs, private label and a due-diligence checklist.
NYC Lab-Grown Supplier Evaluation Checklist
| Check | What a good answer looks like |
|---|---|
| Physical address | A street address and suite number you can confirm independently |
| Visiting policy | Clear appointment process; specific diamonds held for your visit |
| Supplier type | A plain answer on whether they grow, cut, distribute, resell or also manufacture jewelry |
| Growth method | CVD or HPHT stated in writing, including for melee |
| Certification | Labs confirmed for your shapes and sizes; sample certificate on request |
| Owned vs. listed stock | A clear split between diamonds on hand and diamonds sourced on request |
| Matching tolerance | Millimeter and color tolerances for melee and pairs, in writing |
| Shipping cut-off | A stated time and time zone for same-day shipping |
| Returns and memo | Written return window and memo terms for approved accounts |
| Account service | A named contact for reorders and questions |
Red Flags Specific to In-Person NYC Sourcing
Beyond the general warning signs for any wholesale relationship, such as reluctance to provide sample certificates or vague answers about growth method, an in-person New York visit can surface a few more:
- A supplier that repeatedly reschedules or cancels a confirmed appointment.
- A showroom with far less inventory on hand than the website implies.
- A representative who can't speak to certification or shape availability for the diamonds physically in front of you.
- Quotes on "in-stock" diamonds that turn out to need several days to arrive.
- Reluctance to put matching tolerances, return terms or the shipping cut-off in writing.
None of these alone is disqualifying, but a pattern of them during a first visit is a reasonable basis for looking elsewhere before committing a larger order.
FAQ
Which lab-grown diamond manufacturers have a physical presence in the NYC Diamond District?
Many lab-grown growers, cutters, distributors and resellers keep some form of presence on or near 47th Street, ranging from full showrooms with inventory to sales offices only. Guru Diam's showroom is at 36 W 47th St, Suite 601A, open to trade buyers by appointment. Confirm the address, appointment policy and current inventory with any supplier before planning a visit.
Is it worth visiting the Diamond District in person to buy lab-grown diamonds wholesale?
It is most worthwhile for antique cuts, fancy color diamonds, matched pairs and larger orders, where inspecting the diamond adds real value. Routine reorders of standard shapes can usually be handled by phone or online once a supplier relationship is in place.
Do NYC lab-grown diamond suppliers offer certification?
Most offer IGI at minimum, and GIA coverage varies by supplier, shape and size. Guru Diam has 10,000+ IGI/GIA-certified diamonds in stock, and its certified lab-grown diamonds are graded by IGI. Confirm which labs are available on the specific diamonds you need before assuming full flexibility.
What is the difference between a lab-grown diamond grower, cutter and wholesaler?
A grower produces rough lab-grown crystal by CVD or HPHT, a cutter turns rough into polished diamonds, and a wholesaler buys, grades and holds certified inventory for the trade. Some businesses combine stages, and a few also manufacture finished jewelry.
Does Guru Diam only serve New York buyers?
No. Guru Diam has showrooms in New York and Los Angeles, serves 3,000+ trade accounts, ships the same day on orders placed before 6 PM ET, and delivers internationally in 3–4 business days.
Should I call ahead before visiting a Diamond District lab-grown supplier?
Yes. Many suppliers work by appointment only, and confirming inventory, certification and visiting policy ahead of time avoids a wasted trip. Ask the supplier to hold the specific diamonds you want to see.
Can a NYC lab-grown supplier also set the diamonds into jewelry?
Some can. Guru Diam is also a custom jewelry manufacturer: CAD within 24 hours, finished 4–6 working days after CAD approval, no minimum order and payment per piece.
Guru Diam is a trade-only diamond wholesaler and custom jewelry manufacturer at 36 W 47th St, Ste 601A, New York, and 607 S Hill St #241, Los Angeles, supplying natural and lab-grown diamonds and finished fine jewelry to jewelers, retailers, designers and manufacturers. Call +1 (212) 652-7108, apply through trade partner or browse inventory at the wholesale hub.
