A natural blue diamond ring features one of the rarest gemstones on earth — a diamond whose blue colour occurs naturally through trace amounts of boron within its crystal structure. Unlike treated or lab-grown alternatives, a natural blue diamond's colour has existed since formation, deep within the Earth's mantle. Accounting for an estimated less than 0.0001% of all diamonds mined, natural blue diamonds are prized for their breathtaking beauty, extraordinary rarity, and long-term investment value.

Blue diamonds are graded by the GIA (Gemological Institute of America) on a colour intensity scale: Faint → Very Light → Light → Fancy Light → Fancy → Fancy Intense → Fancy Vivid / Fancy Deep / Fancy Dark. The deeper and more saturated the blue, the rarer and more valuable the stone. Fancy Vivid Blue represents the pinnacle of the scale and commands the highest prices at auction. Secondary hues — such as Grayish Blue or Greenish Blue — also affect the grade and price, with a pure, unmodified blue being the most coveted.

There are three distinct types of blue diamonds on the market. Natural blue diamonds are mined from the earth with colour that has existed since formation — no artificial treatment applied. These are the rarest and most valuable. Treated blue diamonds are natural diamonds that have been artificially coloured through irradiation or HPHT processing; while the host stone is natural, the colour is man-made, which significantly reduces value. Lab-grown blue diamonds are manufactured in a laboratory and, while chemically identical, are not mined gems. Japan Diamond carries natural blue diamonds only, all accompanied by GIA or CGL reports confirming "Color Origin: Natural."

Yes. Every blue diamond we carry is accompanied by a grading report from the GIA (Gemological Institute of America) or CGL (Central Gem Laboratory). For blue diamonds specifically, the most critical item to verify is the "Color Origin: Natural" notation, which confirms the colour is not the result of artificial treatment. The certificate also independently verifies the colour grade, clarity, carat weight, and any treatments detected — giving you complete confidence in your purchase.

Platinum (PT950) and 18K white gold are the most popular choices for blue diamond rings, as their cool, neutral tones harmonise beautifully with the stone's blue hue and allow it to take centre stage. 18K yellow gold and rose gold create a striking warm-cool contrast that can be equally stunning and distinctive. For setting style, prong (claw) settings maximise light entry and enhance colour brilliance, while bezel settings offer a sleek, modern look with added protection for everyday wear. Our specialists are happy to guide you toward the ideal combination.

Absolutely. We offer a fully bespoke service where you can select your preferred loose blue diamond and collaborate with our team to design a completely unique ring — choosing the metal type (PT950, 18K white gold, yellow gold, rose gold), setting style, and overall design. Blue diamond engagement rings and anniversary pieces are among our most requested commissions. Browse our loose blue diamond collection to get started, or contact us to arrange a private consultation.

Yes. We welcome private viewings at our Tokyo showroom, where one of our specialists will walk you through each stone in person — examining it under proper lighting and with loupe inspection to fully appreciate its colour and character. For international clients, we offer high-resolution macro photography, video walkthroughs, and live video call consultations. Appointments are required and can be arranged easily through our contact form. Seeing a blue diamond in person is a truly exceptional experience — we highly recommend it.

Yes — a blue diamond engagement ring is a deeply meaningful and increasingly sought-after choice. With a Mohs hardness of 10, diamonds are the most durable natural material on Earth, making them perfectly suited for daily wear. A natural blue diamond combines exceptional beauty with extraordinary rarity, offering a singular alternative to the traditional colourless stone. Worn by royalty and celebrated collectors worldwide, a blue diamond ring is a lasting symbol of love and a genuinely rare treasure. Speak with our team via the contact page to find your perfect stone.

Natural blue diamonds are widely regarded as one of the most stable and appreciating categories within alternative hard assets. Supply is structurally constrained — the Cullinan Mine in South Africa, the world's primary source, reports declining yields, and no significant new blue diamond source has been discovered. Demand from ultra-high-net-worth buyers across Asia, the Middle East, and beyond continues to grow. Landmark auction results — including the Oppenheimer Blue (14.62ct Fancy Vivid Blue, ~$57.5M in 2016) — demonstrate the category's potential. For investment purposes, we recommend prioritising Fancy Intense Blue or above, 1 carat or more, with a GIA report confirming "Color Origin: Natural." Contact our team for a private investment consultation.

Yes. Japan Diamond offers a money-back guarantee on our pieces. Please visit our Money-Back Guarantee page for full details and terms. We want every customer to feel completely confident and satisfied with their purchase — particularly when investing in a stone as significant as a natural blue diamond.