The extraordinary value of a significant colored diamond makes expert advice an imperative when purchasing these relatively small gems. Whether buying from an auction house, diamond dealer, or retail jeweler, you should obtain a gemological certificate that verifies the stone is natural and untreated.
The value of a colored diamond depends primarily on the intensity of its color, which is graded on an industry scale that progresses from faint to fancy vivid. Because there are varying shades within these designations, it is helpful to make side-by-side comparisons with other similarly graded stones to assess a particular gem’s color saturation.
Older stones that are not as deep in color can be recut to align and add facets to enhance intensity, says Rahul Kadakia, head of the jewelry department for Christie’s Americas. “Today, we see more radiant-cut colored diamonds because the added facets help create more brilliance and deeper color.” Still, he adds, as a matter of personal taste, some clients prefer the softer glow of cushion cuts, which have less faceting.
Following color assessment, a stone is evaluated for its cut, size, and history, says Kadakia. “An interesting provenance will certainly make a stone more desirable and valuable.”
Remember that it is extremely unusual to find intensely colored diamonds that weigh more than a few carats. “When it comes to colored diamonds, invest in the best quality you can afford,” advises Sotheby’s Lisa Hubbard. “Forget about the size.”
Those looking to build a collection of fancy colored diamonds might consider narrowing their scope, says John King, the colored diamond expert at the GIA Gemological Laboratory in New York. “Just as a collector of fine art may choose to focus on 20th-century drawings or abstract paintings, a collector of diamonds may take a similar approach.” A collection, for example, could comprise particular sizes, shapes, or colors—or combinations of the three.
“A couple of key points are patience and flexibility,” adds King. “Diamonds are rare, and finding specific examples can be slow, if not impossible.”