Loose Colorless Diamonds

A loose diamond is a diamond in its unset state — not yet mounted in a ring, necklace, or other jewelry piece. Buying loose allows you to evaluate the stone from every angle before committing to a setting, verify the cut, color, and clarity characteristics directly, and then choose or commission the setting around it. Loose diamonds are purchased for custom jewelry creation, jewelry reform, and as long-term asset holdings.

GIA is the world's most internationally recognized gemological laboratory and the only body that formally assigns a cut grade to round brilliant cut diamonds. Its certificates are widely accepted in global diamond markets. CGL is Japan's leading domestic certification body, highly trusted within Japan and issues certificates in Japanese. Both are credible for purchase purposes. If international resale value or recognition is a priority, GIA carries a slight advantage in some markets.

D through F (Colorless) are the most transparent grades with no perceptible warmth — the right choice if the stone will be set in white gold or platinum, or if maximum color purity is the priority. G through J (Near Colorless) appear virtually identical to D-F grades under normal viewing conditions and allow more budget flexibility for carat weight or clarity. For yellow gold settings, G-H color is often indistinguishable from higher grades in practice.

Yes. After selecting a loose diamond, we can create a custom jewelry piece around it — engagement rings, wedding bands, necklaces, and earrings in 18K white gold, yellow gold, rose gold, or platinum. Our craftsmen can produce a sketch before committing to production. Contact us to discuss your design requirements.

Yes. Loose diamonds — particularly GIA certified round brilliant cut stones in D-F color and VVS-VS clarity — have relatively stable long-term value and liquidity in international diamond markets compared to finished jewelry. Investment-grade purchasing is something our team can advise on directly. Please contact us if this is your primary purpose.

Yes. Our appointment-only office is in Okachimachi, Tokyo. Viewing loose diamonds in person — holding them to the light, assessing brilliance and inclusions directly — is significantly more informative than certificate data alone, and we strongly recommend it for purchases above a certain value. Please book an appointment through our contact page or by phone.

Yes. We handle jewelry reform — setting a selected loose diamond into an existing mount, or redesigning an existing piece around a new stone. Please contact us with details of the piece and the stone you are considering, and our team will advise on feasibility and process.