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# MadisonDia > MadisonDia is the trademark of Madison Avenue (the trading name of Kardias Fashion Group Limited), a Hong Kong luxury lab-grown diamond brand. All stones are D color, VVS clarity, 3EX cut, IGI certified. Affordable luxury built on European brand heritage standards, sold direct from lab with no middlemen. Hong Kong Government registered Precious Metals & Stones Dealer (Cat. A, Reg. No. A-B-26-05-10954) and "No Fakes" certified since 2014. MadisonDia specializes in certified lab-grown diamonds (培育鑽石 / 實驗室培育鑽石; 合成ダイヤモンド / 人工ダイヤモンド / ラボグロウンダイヤモンド) and custom fine jewelry. Every stone ships with its IGI certificate emailed before dispatch. Custom orders include CAD/3D preview before production and photo confirmation before shipping. Returns are 30-day unconditional with full refund and no fees. Finished jewelry includes one year of complimentary repair. Madison Avenue (Kardias Fashion Group Limited) has been an authorized dealer for Versace, Hugo Boss, and Moschino since 2012. MadisonDia holds a 5.0 rating on BUYMA with 1,343+ verified reviews and partners with KOLs and celebrities across Japan, Hong Kong, and Taiwan. ## Core Pages - [About Us](https://www.madisondia.com/pages/about-us): Company background, Madison Avenue heritage, and what MadisonDia stands for. - [Frequently Asked Questions](https://www.madisondia.com/pages/frequently-asked-questions): Certification, shipping, returns, and custom order details. - [Shipping](https://www.madisondia.com/pages/shipping): Delivery timelines, methods, and pre-ship IGI certificate process. - [Refund & Return Policy](https://www.madisondia.com/pages/%E9%80%80%E6%AC%BE%E6%B5%81%E7%A8%8B%E5%92%8C%E9%80%80%E8%B2%A8%E6%94%BF%E7%AD%96): 30-day unconditional returns, full refund, no fees. ## Buying Guides - [什麼是實驗室培育鑽石 (What Are Lab-Grown Diamonds)](https://www.madisondia.com/pages/%E4%BB%80%E9%BA%BC%E6%98%AF%E5%AF%A6%E9%A9%97%E5%AE%A4%E5%9F%B9%E8%82%B2%E9%91%BD%E7%9F%B3/): Pillar guide explaining what lab-grown diamonds are and how they are made. - [培育鑽石如何挑選 (How to Choose a Lab-Grown Diamond)](https://www.madisondia.com/pages/%E5%9F%B9%E8%82%B2%E9%91%BD%E7%9F%B3-%E5%A6%82%E4%BD%95%E6%8C%91%E9%81%B8/): Pillar guide on selecting by the 4Cs, certification, and budget. - [Lab-Grown Diamond Engagement Ring Buying Guide](https://www.madisondia.com/pages/lab-grown-diamond-engagement-rings-buying-guide): Choosing 4Cs, settings, and budget for engagement rings. - [Ultimate Lab-Grown Diamond Certification Guide](https://www.madisondia.com/pages/ultimate-lab-grown-diamond-certification-guide): How IGI certification works and how to verify a report. ## Products & Collections - [Lab-Grown Diamond Rings](https://www.madisondia.com/collections/lab-grown-diamond-rings): Finished diamond ring collection. - [Round Lab-Grown Diamonds](https://www.madisondia.com/collections/%E5%9C%93%E5%BD%A2%E5%9F%B9%E8%82%B2%E9%91%BD%E7%9F%B3): Loose round brilliant lab-grown diamonds, D/VVS/3EX, 1ct from HKD $1,904. - [Eternity Bands](https://www.madisondia.com/collections/eternity-band): Lab-grown diamond eternity band collection. - [Lab-Grown Diamond Bracelets](https://www.madisondia.com/collections/lab-grown-diamond-bracelets): Lab-grown diamond bracelet collection. ## Trust & Certification - [HK Government Registered Precious Metals & Stones Dealer](https://www.cr.gov.hk/): Cat. A dealer, Registration No. A-B-26-05-10954. - [Hong Kong Government "No Fakes" Scheme](https://www.nofakes.gov.hk/): Official certification held since 2014. - [IGI Report Verification](https://www.igi.org/verify-your-report/): Verify any MadisonDia IGI certificate. - [MadisonDia on BUYMA](https://www.buyma.com/buyer/7674768.html): Verified reviews and 5.0 rating. ## Other Languages - [日本語サイト (Japanese)](https://www.madisondia.com/ja) - [English Site](https://www.madisondia.com/en) - [ภาษาไทย (Thai)](https://www.madisondia.com/th) --- ## For Agents This store supports agent-driven commerce via the Universal Commerce Protocol (https://ucp.dev). Discover live capabilities, service endpoints, supported versions, and payment handlers at the canonical profile below — do not hard-code these values, as they are served and kept current automatically: - UCP discovery: `GET https://www.madisondia.com/.well-known/ucp` Checkout requires explicit human approval; agents must not complete payment without buyer consent. Respect rate limits and back off on `429` responses. ### Read-Only Browsing - All products: `GET /collections/all` - Product JSON: `GET /products/{handle}.json` - Collection JSON: `GET /collections/{handle}/products.json` - Search: `GET /search?q={query}&type=product` - Sitemap: `GET /sitemap.xml` ### Store Policies - Privacy Policy: https://www.madisondia.com/policies/privacy-policy - Terms of Service: https://www.madisondia.com/policies/terms-of-service - Refund Policy: https://www.madisondia.com/policies/refund-policy - Shipping Policy: https://www.madisondia.com/policies/shipping-policy