Frequently Asked Questions

Are rare diamonds a good investment?

Rare diamonds are best thought of as collectibles with a long record of holding value — not as a financial product with predictable returns. The most widely cited long-run measure is the Fancy Color Research Foundation price index. As reported by the Natural Diamond Council, it shows top pink diamonds up about 394%, blue diamonds up about 242% and yellow diamonds up about 49% over roughly twenty years.

Those are index averages for fine stones over a long period, not a forecast for any single diamond. Prices can fall as well as rise, there is no public exchange, and selling takes time and carries commissions. Our Diamond Investment Guide and auction records set out the wider picture.

How do the colors compare?

Pink: supply tightened sharply after the Argyle mine in Western Australia — the source of about 90% of the world's pink diamonds — closed in November 2020. Blue: the rarest of the three, with the highest per-carat prices at auction, but so few trades that price data is thin. Yellow: the most available fancy color, with lower entry points and more frequent trading. Which suits you depends on your budget and what you love; we do not recommend a fixed split between colors. The fancy color overview covers each in more depth.

What size diamond should I consider?

There is no single threshold. In every color, rarity rises steeply with size, so larger stones are scarcer and generally command higher prices per carat — but they also take longer to sell. Color grade often matters more than weight: a smaller Fancy Vivid can be worth more than a larger Fancy Light. Our guide to the GIA fancy color grading system explains why, and we are happy to talk through the trade-offs in a consultation.

How long does it take to sell a rare diamond?

Through major auction houses (Christie's, Sotheby's, Bonhams), consignment to sale commonly takes several months, because sales run on a seasonal calendar. Private sales through dealer networks can be quicker but may require price flexibility. Auction houses and dealers charge fees, so the hammer or sale price is not what the seller receives. Our resale support services assist clients with both routes.

How do I verify a diamond is genuine and natural?

Ask for a GIA report that identifies the diamond as natural and, for a fancy color, states that the color origin is natural. Check the report number on GIA's online Report Check, and match the laser inscription on the girdle where there is one. Diamond type alone does not prove natural origin — laboratory-grown blue diamonds are also Type IIb — which is why the laboratory report matters. For Argyle pinks, original Argyle documentation adds provenance. Every diamond we offer comes with its GIA report and our own authentication documentation.

What is the difference between natural and treated diamonds?

Natural fancy color diamonds owe their color to conditions during formation — boron for blue, nitrogen for yellow, and lattice distortion (plastic deformation) for pink. Treated diamonds are usually lower-grade stones whose color has been created or enhanced by HPHT (high pressure, high temperature), irradiation and annealing, or coating. Treated stones sell for a small fraction of natural equivalents. GIA reports disclose any treatment detected. We sell only natural, untreated diamonds.

What is Type IIa / Type IIb and why does it matter?

Type IIa diamonds contain little or no detectable nitrogen — an estimated 1–2% of natural diamonds — and many of the world's largest and finest colorless diamonds are Type IIa. Type IIb diamonds contain boron, which causes blue color and makes them electrically conductive; most natural blue diamonds are Type IIb. Type Ib diamonds contain isolated nitrogen, which gives a rich, saturated yellow; Zimmi diamonds are known for it. Type describes the crystal chemistry, not origin — most laboratory-grown diamonds are also Type IIa or IIb.

Why do you work with GIA reports?

GIA introduced the D-to-Z color scale in 1953 and developed the fancy color grading system the trade uses today. Its reports are the reference most auction houses and dealers rely on, and it runs one of the largest research programs on treatment and laboratory-grown detection. Grades from different laboratories are not always comparable, so we keep every comparison on the same GIA basis. Learn more on our Grading & Certification page.

Should I prioritize Argyle pink diamonds?

Argyle pink diamonds are prized for their provenance — especially stones from the annual Argyle Pink Diamonds Tender, which came with Argyle documentation and a laser inscription. With the mine closed since 2020, there is no new Argyle production. How much provenance adds depends on the color, size and documentation of the individual stone. If your priority is the beauty of the color, non-Argyle pinks can offer lovely stones at different price points.

What is a "canary" diamond?

"Canary" is an informal trade term, not a GIA grade. It is generally used for yellow diamonds with strong, pure color — typically Fancy Intense or Fancy Vivid Yellow with no secondary hue. Every canary diamond is a yellow diamond, but not every yellow diamond is described as canary.

What makes Zimmi diamonds special?

Zimmi diamonds are yellow diamonds from the Zimmi area of Sierra Leone, known for an intense, saturated yellow linked to isolated nitrogen. Research published by GIA describes them as typically mixed Type Ib-IaA. Diamonds with a strong Type Ib character are rare among yellow diamonds, which is why Zimmi stones are sought by collectors.

What is "plastic deformation" in pink diamonds?

Plastic deformation is a permanent distortion of the diamond's crystal lattice caused by intense stress deep in the earth. In pink diamonds it is linked to the absorption band that produces the color, and it also plays a part in many brown diamonds. Unlike blue (boron) or yellow (nitrogen), pink comes from the crystal's structure rather than a trace element — and scientists are still studying exactly how. Learn more in our Science of Diamond Color guide.

Do I need to purchase a diamond to receive a consultation?

No. Private consultations are complimentary and without obligation. Our goal is education and building relationships. Many clients meet with us several times over months or years as they refine their understanding and preferences before making an acquisition.

What is the minimum budget for your services?

We work with a range of budgets. Our collection focuses on significant natural rare diamonds, and our custom sourcing service can search to your criteria and objectives at different price levels.

How do your prices compare to other dealers?

We price against current market values, auction results and dealer networks. Our pricing is transparent — we explain how a price was reached, including comparable sales. We welcome informed comparison.

Can you help me sell a diamond I already own?

Yes. We offer evaluation and resale support services for exceptional diamonds, whether purchased through us or elsewhere. We connect sellers with qualified buyers, auction houses and international dealers to seek the best available price.

Do you work with clients outside the United States?

Yes. We serve clients worldwide via virtual consultations (Google Meet preferred) and fully insured international shipping. We accommodate consultations across all time zones. Hand delivery is available where possible for significant acquisitions.

How long does the sourcing process take?

It depends entirely on the criteria. Many searches take weeks to a few months; exceptionally rare specifications — large Fancy Vivid blues, Argyle Tender pinks, fine Zimmi yellows — can take a year or more. We provide regular updates throughout the search and never compromise quality for speed.

Should I have my diamond set in jewelry?

Many significant diamonds are set in fine jewelry so they can be enjoyed. We recommend platinum or 18K gold settings designed so the stone can be removed easily if you ever wish to sell it. Explore our jewelry design services.

Can rare diamonds be worn daily?

Yes. Diamond is the hardest natural material and resists scratching, though it can chip if struck hard on an edge. A secure setting with an annual inspection and appropriate insurance makes daily wear practical. See our care guide for detailed recommendations.

All consultations are complimentary and without obligation. We build long-term relationships based on education, trust, and exceptional service.

All information provided is for educational purposes. RARE.DIAMONDS does not provide investment advice. Clients should consult qualified financial advisors before making significant asset allocation decisions. Past performance does not guarantee future results.

Sources: Natural Diamond Council, Fancy Color Diamonds report (Fancy Color Research Foundation index data); Rio Tinto (Argyle closure, November 2020); GIA (grading history, diamond type, Zimmi research).