Frequently Asked Questions

MadisonDia is a Hong Kong-based lab grown diamond brand operated by Madison Avenue — a luxury retail company that has been an authorised boutique dealer for Versace, Hugo Boss, and Moschino since 2012. We are not a marketplace, a platform, or a reseller. We source directly from leading laboratories and manufacture finished jewellery through our own production partners.

What that means for you: every diamond meets a fixed, uncompromised standard (D color · VVS · 3EX · IGI-certified), there is no upselling or tiered quality, and pricing reflects direct sourcing — not retail markup. We have earned a 5.0 rating on BUYMA with 1,343+ verified reviews from customers across Japan, Hong Kong, Taiwan, and beyond.

Yes. Madison Avenue (our parent company) holds the Hong Kong Government's official No Fakes Pledge certification — a consumer protection programme certifying that we sell only genuine, accurately described goods. We have maintained this certification since 2014.

We are also registered under Hong Kong's Precious Metals and Stones Dealer regulations (Cat. A — Reg. No. A-B-26-05-10954).

Traditional jewellery retail involves multiple layers: miners, polishers, wholesalers, importers, and then the retailer. Each layer adds margin. We work directly with laboratories and manufacturing partners, which removes every unnecessary middleman.

The result: our D/VVS2/3EX IGI-certified diamonds are priced to reflect direct sourcing — not retail markup. Traditional retailers selling the same specification typically charge several times more with no difference in the diamond itself.

MadisonDia operates as an online brand. You can browse our full catalogue, review IGI certificates, and place orders entirely online. Our team is available via WhatsApp, email, and live chat to guide you through every step.

Yes — all 1,343+ reviews on BUYMA are from verified buyers who completed real purchases. BUYMA is Japan's largest overseas shopping platform and independently records every transaction. Our rating is 5.0 / 5.0. You can read the reviews directly on our BUYMA seller profile.

Lab grown diamonds are real diamonds — not simulations, not imitations. They are chemically, physically, and optically identical to mined diamonds: pure carbon atoms arranged in the same crystal structure, with the same hardness (10 on the Mohs scale), the same refractive index, and the same brilliance.

The only difference is origin. Mined diamonds form over billions of years under extreme pressure deep in the earth. Lab grown diamonds replicate that same process in a controlled environment — in weeks rather than millennia. Both GIA and IGI certify lab grown diamonds using the same 4C grading standards as mined stones.

Common simulants like moissanite and cubic zirconia (CZ) are chemically different from diamond and are not lab grown diamonds. If a seller cannot provide an IGI or GIA grading report for the stone they are selling, do not assume it is a diamond.

Physically, no. Diamond is the hardest natural material on earth (Mohs 10). A lab grown diamond will not scratch, fade, or change in appearance with daily wear — ever. It is the same material as a mined diamond and will last just as long.

In terms of resale value: like mined diamonds, lab grown diamonds do lose a significant portion of their retail value on the secondary market. We are transparent about this. Most customers buying an engagement ring or fine jewellery piece do not plan to resell it — but if that is a consideration, it is important to understand upfront.

Not with the naked eye, and not with a standard diamond tester — which only confirms a stone is a diamond (as opposed to CZ or moissanite). Distinguishing a lab grown diamond from a mined diamond requires specialist equipment not available in most jewellery shops.

This is actually why certification matters so much: your IGI report clearly states whether a diamond is lab grown, so there is no ambiguity for you or anyone you share it with.

Lab grown diamonds avoid the land disruption, water usage, and community displacement associated with traditional diamond mining. They do require energy to produce — and the environmental footprint depends partly on the energy source used by each laboratory.

For buyers who care about supply chain ethics, lab grown diamonds offer a fully traceable origin — unlike mined diamonds, which pass through many hands before reaching a consumer.

Every diamond we stock meets the same fixed specification — no tiers, no compromises:

We do not stock lower-colour or lower-clarity stones. There is no upselling here — every diamond you see is already at the top of the range.

The International Gemological Institute (IGI) is one of the world's leading independent gemological laboratories. An IGI certificate is issued by gemologists who have no commercial relationship with the diamond seller — they assess and record a stone's exact color, clarity, cut, carat weight, and fluorescence on a standardised international scale.

Why it matters: without an independent certificate, a seller can describe a diamond's quality in any terms they choose. With an IGI report, the grade is objective, verifiable, and internationally recognised. Every MadisonDia diamond comes with its certificate number — you can verify it yourself at igi.org at any time.

MISI™ (MadisonDia Ideal Sparkle Index) is our proprietary light-performance scoring system, developed with IGI-certified gemologists, mathematicians, and optical engineers. The 4Cs tell you about a diamond's physical properties — MISI™ tells you how much it will actually sparkle in real light.

MISI™ evaluates brilliance (white light return), fire (colour dispersion), and scintillation (sparkle pattern) and converts them into a score out of 100. We only stock diamonds that score 80 or above. Currently MISI™ applies to round brilliant cut diamonds — it is not designed for fancy shapes or Hearts & Arrows optical symmetry evaluation.

The GIA color grading scale runs from D (completely colorless) to Z (light yellow). D is the highest possible grade — a diamond that appears entirely white and transparent, with no visible tint even under magnification.

Most diamonds sold in jewellery retail are G–H color, which appear near-colorless to the naked eye but are not truly colorless. We stock D–E only. In a side-by-side comparison under light, the difference in whiteness is visible — particularly once the diamond is set in white gold or platinum.

VVS (Very Very Slightly Included) means the diamond contains minute inclusions that are extremely difficult to see even under 10× magnification by a trained gemologist — invisible to the naked eye. VVS1 and VVS2 are the two top clarity grades below the rare Flawless and Internally Flawless categories.

For most buyers, VVS clarity is the practical sweet spot: the diamond looks completely clean in person and in photographs, but you are not paying for Flawless-grade rarity that offers no visible benefit. We do not stock VS or below.

Our pricing changes regularly as the market moves, so we keep live prices on the catalogue page rather than quoting fixed figures here. All stones are D–E color, VVS1–VVS2 clarity, Triple Excellent cut, and IGI certified.

The price difference is significant. A 3ct D/VVS2 natural diamond typically retails above USD $60,000–$112,000 depending on cut and provenance. The equivalent lab grown stone from MadisonDia is a fraction of that — the same chemical material, the same IGI certification standard.

The savings come from supply chain efficiency, not from any reduction in quality. The stone itself is indistinguishable from a mined diamond under any standard testing available to jewellery retailers.

Lab grown diamond prices have generally decreased over time as production technology improves and supply increases. There is no guarantee prices will rise. If you have found a stone at a specification and price that works for you, that is typically the best time to buy. Waiting in expectation of a better deal is uncertain.

Japan customers: We cover import duties on your behalf. Please note that Japanese consumption tax is not included and remains the buyer's responsibility.

All other countries: MadisonDia ships from Hong Kong. Import duties and local taxes are governed by your country's regulations and are the buyer's responsibility. We include all required documentation (IGI certificate, commercial invoice, declared value) to facilitate smooth customs clearance.

If you have questions about duties for your country, contact us before ordering and we will advise based on recent experience.

1. Choose your diamond — browse our catalogue and select a carat, or contact us for a recommendation.
2. We email your IGI certificate — before anything ships, we send your stone's full grading report for review.
3. Approve or request alternatives — if you want to see other options, we present at least 5 alternatives of equivalent grade at no extra cost.
4. We confirm and ship — once you are happy, your diamond or jewellery is dispatched via insured courier.
5. Delivery with documentation — your parcel arrives with the original IGI certificate and all relevant paperwork.

Yes — this is standard practice for us. Once you place an order, we email you the full IGI grading report of your selected stone. You can review the certificate and verify it independently at igi.org before we ship anything. If the stone does not meet your expectations, you can request alternatives or a full refund.

Yes. We offer fully bespoke rings, pendants, and earrings. The process works as follows:

• Share your design reference or describe what you have in mind
• Our team produces a CAD/3D preview for your approval
• You select your diamond from our catalogue (IGI certificate sent for review)
• Production takes 5–15 business days
• We send photos of the finished piece before dispatch

We email your IGI certificate before shipping, so you review the stone's specification in advance. If the certificate does not match your expectations, we will present at least 5 alternatives of the same grade. If none of those work for you either, you are entitled to a full refund with no fees — even before anything has been sent.

If the diamond has already been delivered, our 30-day return policy applies (see Returns section below).

We accept all major cards and digital wallets:

All card payments are processed via Stripe with full SSL encryption. We do not store payment details.

• Former Madison Avenue customers — contact our team directly to request a dedicated code.
• KOL / influencer codes — personal codes are shared by each influencer on their social media. Please request them directly from the creator.

Yes. We ship worldwide from Hong Kong using fully insured couriers: DHL, FedEx, EMS, and SF Express. Every shipment includes the original IGI certificate and all customs documentation. Current regular destinations include Japan, Hong Kong, Taiwan, Singapore, Thailand, Australia, the USA, Canada, and the UK.

• Loose diamonds: 0–2 business days processing + 2–8 business days shipping
• Custom jewellery: 5–15 business days production + 2–8 business days shipping

Customs clearance times are outside our control and may add extra days in some countries. We send tracking information as soon as your parcel is dispatched.

Yes. Every shipment is fully insured for the declared value of its contents. In the extremely unlikely event of loss or damage in transit, we will handle the claim on your behalf. You will not be left out of pocket.

• Loose diamonds: Full refund within 30 days of delivery — no questions asked, no fees.
• Finished jewellery: Store credit refund within 14 days. A polishing/handling fee of USD $25–40 applies. Item must be returned in original condition with all certificates and packaging.

Free return shipping is available for customers in: Japan, Hong Kong, Macau, Taiwan, United Kingdom, United States, Canada, and Australia.

If your country is not listed, return shipping costs may apply. Please contact us before sending anything back so we can advise on the best process.

Once we receive your returned item, we inspect it within 1–3 business days. Refunds are then processed immediately and typically appear in your account within 3–10 business days, depending on your payment method and bank. We will email you as soon as the refund has been issued.

Yes. Every finished jewellery piece comes with a complimentary 1-year repair service covering manufacturing defects and normal wear. If a prong loosens or a setting requires attention within the first year, we will repair it at no charge.

For ongoing care: we recommend annual professional cleaning and prong checks for any diamond jewellery, regardless of where it was purchased.

Most solitaire and simple band designs can be resized. Complex pavé or eternity settings are more difficult to resize without affecting the setting integrity. If you are unsure about your ring size before ordering, contact our team — we can advise on the best approach for your chosen design and arrange resizing if needed.

• What is a lab grown diamond? — the complete beginner's guide
• How to choose a lab grown diamond — 4Cs explained, what to prioritise
• Lab grown diamond certification guide — IGI vs GIA, what the report means
• Engagement ring buying guide — settings, metals, budget planning
• Browse all diamond guides →