Guru Diam is a trade-only wholesale lab-grown and natural diamond supplier with showrooms in New York (36 W 47th St, Diamond District) and Los Angeles (607 S Hill St), holding 10,000+ IGI/GIA-certified diamonds in stock and shipping the same day on orders placed before 6 PM ET. Its certified lab-grown diamonds are graded by IGI, lab-grown production is primarily CVD, and there is no minimum order. The same account covers loose diamonds, matched melee and pairs, and finished jewelry produced in-house in New York and India.
Browse every size and setting in our Essential Basic Jewelry Catalog, with trade prices for verified jewelers.
Choosing a wholesale lab-grown diamond supplier shapes a jeweler's or manufacturer's inventory, margins and customer relationships for years, not just one order. This guide is for trade buyers. Rather than a ranked list of names, it explains the main types of wholesale lab-grown suppliers, the criteria that matter in a recurring B2B relationship, and how to vet any supplier before you commit volume. 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 |
| Locations | New York: 36 W 47th St, Ste 601A (Diamond District). Los Angeles: 607 S Hill St #241. Showroom visits by appointment. |
| Diamonds | Natural and lab-grown; 10,000+ IGI/GIA-certified diamonds in stock; standard, antique and exotic shapes |
| 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; lab-grown matched pairs in all shapes |
| 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 |
What to Evaluate in a Wholesale Lab-Grown Diamond Supplier
| Criterion | What to look for |
|---|---|
| Shape and cut range | Round brilliant plus fancy and antique cuts, not round-only inventory |
| Growth method | CVD or HPHT stated in writing, including for melee |
| Certification | Which lab grades the lab-grown diamonds you'll buy, confirmed for your shapes and sizes |
| Owned stock | How much inventory is on hand vs. listed from partners |
| Shipping speed | A stated same-day cut-off and time zone |
| Catalog breadth | Loose diamonds, melee and finished jewelry under one account vs. a single-category specialist |
| Matching | Written tolerances for melee and pairs |
| Minimum order | Whether small trial orders are accepted |
| Account terms | Memo, returns, payment methods and credit terms |
The Types of Wholesale Lab-Grown Diamond Suppliers
Ranked lists of names go stale quickly and say little about fit. Most suppliers you'll meet fall into one of five types, and knowing which one you're talking to tells you what to expect.
1. Single-category specialists
Some suppliers focus on one category: certified solitaire sizes, melee, fancy color or a particular shape group. Within that category they can be very deep. Outside it, you'll need another supplier. Ask what share of their inventory is in the category you need, and what happens when you need something outside it.
2. Broad-catalog wholesalers
Broad-catalog wholesalers hold certified diamonds, melee, fancy shapes and sometimes natural diamonds under one account. Their advantage is consolidation: fewer vendor relationships, one set of terms, one account manager. Ask how deep each category really is, not just whether it appears on the menu.
3. Melee and calibrated-size specialists
Melee suppliers focus on small diamonds in calibrated sizes for pavé, halos and bands. Matching and consistency across reorders are what matter here. Ask for the millimeter tolerance in writing and how they keep a size consistent from one order to the next.
4. Listing-only and marketplace sellers
Some sellers hold little inventory and list diamonds from other suppliers' feeds. They can widen a search for a one-off request but rarely control timing, matching or certification turnaround. Ask who physically holds the diamond and who ships it.
5. Wholesalers that also manufacture jewelry
Some wholesalers supply loose diamonds and also produce finished jewelry. For jewelers who need diamonds set into custom pieces, this removes a hand-off between two businesses. Ask for CAD turnaround, production time, where production happens and any minimum order.
| Supplier type | Typical strength | Key question |
|---|---|---|
| Single-category specialist | Depth in one category | What happens when I need something outside it? |
| Broad-catalog wholesaler | Consolidation under one account | How deep is each category? |
| Melee specialist | Calibrated sizes and matching | What tolerance, in writing? |
| Listing-only seller | Search reach | Who holds and ships the diamond? |
| Wholesaler + jewelry manufacturer | Diamonds and finished pieces from one account | What are the CAD and production timelines? |
Where Guru Diam Fits
Guru Diam is a broad-catalog wholesaler that also manufactures jewelry. It holds 10,000+ IGI/GIA-certified natural and lab-grown diamonds in stock across standard, antique and exotic shapes, plus melee, matched pairs, fancy color and 3,000+ finished jewelry pieces ready to ship. Certified lab-grown diamonds are graded by IGI, lab-grown production is primarily CVD, and lab-grown melee is CVD Type IIa.
When a diamond isn't in stock, Guru Diam sources it, or has it cut, to specification. Melee is matched to ±0.05–0.10 mm and pairs to ±0.1–0.2 mm, about one color grade, and lab-grown matched pairs come in all shapes. Jewelry production is in-house in New York and India, with a CAD within 24 hours and a finished piece 4–6 working days after approval. There's no minimum order. Browse the wholesale hub or apply through trade partner.
Why the Right Supplier Depends on What You Stock
No single wholesale lab-grown supplier is best for every buyer. A jeweler focused on round brilliant engagement center diamonds has different priorities from a manufacturer building antique-cut jewelry or a retailer specializing in fancy color. Catalog breadth, certification and shipping reliability matter to nearly everyone, but if you have a narrow specialty, weight that category more heavily. For antique and exotic shapes specifically, see our antique-cut lab-grown diamond supplier guide.
How Catalog Breadth Affects a Recurring Relationship
A buyer sourcing only round melee for one product line may not need much breadth. Most jewelers and manufacturers eventually need fancy or antique shapes, natural diamonds or finished pieces at least occasionally. A supplier that can't extend into those categories forces a second or third vendor relationship just to cover gaps.
Consolidating under fewer suppliers with genuinely broad catalogs cuts the administrative and quality-control overhead of managing many vendors. That's a real advantage independent of any single order's price.
CVD vs. HPHT: Why Growth Method Matters to a Buyer
CVD (chemical vapor deposition) and HPHT (high pressure, high temperature) are the two commercial methods for growing lab diamonds. Both produce real diamonds with the same chemical and physical properties as natural diamonds. The method still matters to a buyer because it can affect color behavior, inclusion types and what a grading report notes.
If you're building a consistent product line, know which method your supplier's inventory uses rather than working from a mixed, unlabeled catalog. Guru Diam's lab-grown production is primarily CVD, and its lab-grown melee is CVD Type IIa.
Certification Across the Wholesale Market
IGI is the most commonly available lab for lab-grown diamonds across the wholesale trade, given its long specialization in lab-grown grading. Guru Diam's certified lab-grown diamonds are graded by IGI. If your retail customers expect a specific lab, confirm what a supplier can deliver on the exact shapes and sizes you sell, not what it lists as available "on request" with added delay.
Ask for a sample report, verify the report number on the lab's website and match it to the girdle inscription. Browse certified lab-grown diamonds to see report details before ordering.
Same-Day Shipping: Why It Matters More Than It Sounds
Shipping speed on confirmed in-stock inventory decides how quickly you can fill a customer's custom order or restock a fast-moving item, and the gap between same-day and multi-day shipping compounds over a year of reorders. Confirm the actual cut-off time and time zone, not just "same day" as a general claim.
Guru Diam ships the same day on orders placed before 6 PM ET, which is 3 PM Pacific, and international delivery takes 3–4 business days.
Minimum Orders and Trial Orders
A new buyer testing a supplier benefits from placing a modest trial order before committing serious capital. Suppliers with large minimums from day one make it harder to vet quality, communication and shipping firsthand, which is worth weighing against any per-unit price advantage. Guru Diam has no minimum order and work is paid per piece.
Natural Diamonds Alongside Lab-Grown
Many jewelers now stock natural and lab-grown diamonds side by side to serve customers with different budgets and preferences. A supplier offering both under one account is increasingly valuable compared with a lab-grown-only specialist. If you expect to need natural diamonds even occasionally, factor that in now rather than adding a vendor later. Guru Diam carries both; see natural certified diamonds and lab-grown diamonds.
East Coast, West Coast and In-Person Buying
New York's Diamond District remains the historic center of the US diamond trade, and many wholesale lab-grown suppliers are based there. Some also keep a West Coast presence, which helps buyers who want to see diamonds in person without flying east. Ask any supplier where its showrooms are, whether visits are by appointment, and where your order actually ships from.
Guru Diam has showrooms in New York and Los Angeles, open by appointment through book appointment. For the New York picture, see lab-grown diamond manufacturers in NYC; for the national view, see lab-grown diamond manufacturers in the USA.
Pricing: What Drives Per-Carat Differences
Per-carat pricing varies with growth method, shape and cut complexity, certification cost included in the quote, and each supplier's overhead and margin. The lowest headline price isn't automatically the best value once certification, shipping reliability and catalog breadth are counted. Confirm what's included in each quote, such as certification, shipping and any setting work, before treating two per-carat numbers as comparable. Quotes that look far apart sometimes converge once every cost is counted on both sides.
What "Trade-Only" Means in Practice
Most wholesale lab-grown suppliers are trade-only: access requires a verified business account, usually with a resale certificate, business license or equivalent documents, rather than walk-in consumer sales. Setup requirements, verification time and ongoing account terms vary, and they affect how soon you can place orders. Guru Diam trade applications submitted through trade partner before 4 PM ET are approved the same business day, otherwise the next business day.
Reorder Consistency
A useful wholesale relationship depends on whether the supplier can reproduce the same specification months later. That matters for any retailer with a standing product line. Ask how the supplier keeps grading and sizing consistent on a specific melee size or specification across orders; inconsistency here is one of the most common reasons retailers switch suppliers after a good first order. Written matching tolerances, like Guru Diam's ±0.05–0.10 mm on melee, make reorders easier to check.
Account Managers and Integration
Recurring accounts usually work best with a dedicated contact rather than a general order desk. A representative who understands your product line can flag relevant new inventory, resolve order issues quickly and keep reorders smooth. Ask who you'll work with day to day. Every Guru Diam trade account has a dedicated account manager.
If you list diamonds on your own website, ask about inventory feeds. Guru Diam offers API and CSV feed integration for trade partners; see inventory access.
Melee: Sizes, Matching and Consistency
Melee is where many wholesale relationships succeed or fail. Pavé, halos, eternity bands and tennis pieces need hundreds of small diamonds that look like one set, so a supplier's matching discipline matters as much as its price per carat. Ask how melee is sized and sorted, what millimeter tolerance applies, how color and clarity ranges are grouped, and whether the same parcel specification can be repeated on a reorder.
Growth method matters here too, because mixed melee from different growth methods can behave differently in color. Guru Diam's lab-grown melee is CVD Type IIa, matched to ±0.05–0.10 mm. See round melee and pointers and fancy color melee.
Melee matching is most visible in line jewelry. Our diamond tennis bracelet wholesale guide and diamond tennis necklace wholesale guide cover sizes, settings and the 2–30 ct total weight range we make.
Fancy Color Lab-Grown Diamonds
Fancy color is a specialist category inside lab-grown wholesale. Most suppliers list some colors, but depth across colors, shapes and sizes varies widely, and matched fancy color sets are harder still. Ask which colors are stocked in depth, which sizes are available in each, and whether pairs and layouts can be matched by color. Guru Diam's fancy color range covers seven colors: Black, Blue, Brown, Green, Pink, Red and Yellow. See fancy color certified diamonds.
Finished Jewelry From Your Diamond Supplier
Many jewelers buy loose diamonds from one business and send them to another for setting. That works, but it adds a hand-off, a second set of terms and another place for a delay. A wholesaler that also manufactures jewelry can take a design from CAD to finished piece with diamonds from its own inventory. Ask where production happens, how long CAD and production take, and whether there's a minimum. Guru Diam's jewelry production is in-house in New York and India, with a CAD within 24 hours, a finished piece 4–6 working days after approval (complex pieces may take 2–3 weeks), metals in 14K and 18K gold, silver and platinum, and no minimum order. Start at custom jewelry.
For a deeper look at choosing a manufacturing partner, see our guide to the best custom jewelry manufacturers for the wholesale trade and, if you buy in New York, our NYC custom jewelry manufacturer guide.
Building a Primary and Backup Supplier Strategy
Even buyers happy with a primary supplier benefit from at least one qualified backup, because stock gaps, shipping delays or price shifts can affect any supplier. A backup doesn't need equal volume; an occasional small order keeps the relationship active and confirms fit, so there's a real fallback ready when a time-sensitive order can't wait.
How to Vet a New Supplier Before Committing Volume
Beyond the criteria above, request sample certificates, ask about matching practices for melee, and place at least one modest trial order to test communication and fulfillment speed. Speak with the account manager you'll actually work with rather than relying on website claims. Day-to-day account service varies more between suppliers than catalog comparisons reveal, and a responsive, knowledgeable contact often matters more than a small per-carat difference. Memo terms and a written return window, such as Guru Diam's 14-day free return, lower the risk of a first order.
Wholesale Lab-Grown Supplier Checklist
| Check | What a good answer looks like |
|---|---|
| Supplier type | A plain answer: specialist, broad wholesaler, melee specialist, listing-only, or wholesaler plus manufacturer |
| Growth method | CVD or HPHT in writing, including melee |
| Certification | The lab named for your shapes and sizes; sample report on request |
| Owned stock | Diamonds on hand vs. sourced on request, clearly separated |
| Matching | Millimeter and color tolerances in writing |
| Shipping | Same-day cut-off and time zone; international transit time |
| Minimum order | Trial orders accepted, or the minimum stated |
| Returns and memo | Written return window; memo terms for approved accounts |
| Payment | Payment methods and credit terms for established accounts |
| Account service | A dedicated contact; inventory feed if you need one |
Red Flags in a New Supplier Relationship
- Reluctance to provide sample certificates before a first order.
- Vague or shifting answers on CVD vs. HPHT for specific diamonds.
- Certification turnaround much longer than first described.
- "In-stock" diamonds that turn out to need several days to arrive.
- No written matching tolerance or return policy.
None of these alone disqualifies a supplier, but a pattern of evasiveness on questions with straightforward answers is a stronger signal than any single flag.
How Trade Shows Fit Into Supplier Discovery
Trade shows remain one of the most efficient ways to meet several wholesale suppliers in person, compare inventory side by side and start a relationship with the people who'll actually serve your account. Treat a show as a research trip: bring the criteria in this guide and compare before committing on the floor. Our JCK Las Vegas buyer's guide covers show planning.
Questions to Ask Before Opening a Wholesale Account Anywhere
Bring this list to the first real conversation with any prospective supplier, and get answers in writing wherever possible:
- Which certification labs do you use, and is certification per-stone or per-parcel?
- Is the inventory I'm quoted on physically in your possession right now, and where is it held?
- What is your minimum order — per stone, per dollar amount, or per category — and does it change for fancy colors, antique cuts, or melee?
- What is your actual turnaround on loose stones, and what's your defined lead time on custom or finished pieces?
- Do you offer memo or consignment terms, and what's the return window in writing?
- How do you share live inventory — a portal, an API/feed, or a manually updated list — and how often is it refreshed?
- Who is my dedicated point of contact, and what's the escalation path if a cert or shipment has a problem?
- Can you provide two or three trade references from accounts of a similar size to mine?
- What happens, contractually, if a certificate turns out to be inaccurate after the sale?
- Do your prices and terms differ for a new account versus an established one, and for how long?
Onboarding Checklist: Opening a Wholesale Account
Once you've evaluated and test-ordered from a supplier, opening the account itself is mostly documentation and setup. Work through this before your first real order:
- Business documentation. Resale certificate, business license, and any trade-association or jeweler credential the supplier requires to extend trade pricing.
- Trade references. Have two or three ready if the supplier asks — and ask for the same in return.
- Category scope. Decide up front which categories you'll actually source from this supplier (loose rounds, fancy shapes, melee, finished custom) versus what stays with an existing vendor.
- Pricing and MOQ in writing. Get the rate structure and minimum order terms confirmed in writing before your first order, not verbally on a call.
- Return, memo, and consignment terms. Confirm the written policy, not just a verbal assurance, before you need to use it.
- Trade tool access. Set up portal or API access immediately if you sell online — don't launch on a manually emailed list and switch later.
- Point of contact and escalation path. Know who to call for a routine order and who to escalate to if something goes wrong.
- First test order. Place it before you route real customer orders through the new account, and evaluate it against everything above.
Buying from Canada, Australia or the UK? See our trade pages for diamond wholesaler Canada, wholesale jewellery Australia and wholesale jewellery UK, with same-day dispatch from New York and international delivery typically in 3–4 business days.
FAQ
How should a new jeweler choose a wholesale lab-grown diamond supplier?
Look for catalog breadth across standard, antique and fancy shapes, clear certification and growth-method answers, a small or no minimum order, and a stated same-day shipping cut-off. Then test with a modest trial order.
Do all wholesale lab-grown suppliers offer the same certification?
No. Lab coverage varies by supplier, shape and size. Guru Diam's certified lab-grown diamonds are graded by IGI; confirm the lab on the specific diamonds you're ordering with any supplier.
Is CVD or HPHT better for wholesale sourcing?
Both produce real diamonds. What matters most for a consistent product line is knowing which method a supplier uses. Guru Diam's lab-grown production is primarily CVD, and its lab-grown melee is CVD Type IIa.
Should I source from one supplier or several?
Most buyers do best with one broad primary supplier plus at least one qualified backup, since stock gaps or delays can affect any single supplier.
Is there a minimum order for wholesale lab-grown diamonds?
It depends on the supplier. Guru Diam has no minimum order and work is paid per piece.
Do wholesale suppliers offer both natural and lab-grown diamonds?
Some do and some specialize in one. Guru Diam carries both natural and lab-grown diamonds, plus finished jewelry.
What do I need to open a wholesale trade account?
Usually a resale certificate, business license or equivalent documents. Guru Diam approves applications submitted before 4 PM ET the same business day, otherwise the next business day.
How fast do wholesale lab-grown suppliers ship?
Cut-off times vary. Guru Diam ships in-stock diamonds the same day on orders placed before 6 PM ET, with international delivery in 3–4 business days.
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.
