Gemstones & cuts
Colored stones: sapphire, emerald, ruby and garnet
Which colored stones turn up in which era, and what treatment means for value.
Written by our in-house jewelry team · Updated August 1, 2026 · 8 min read
In short
Colored stones date a piece nearly as reliably as its metal: flat-cut, closed-back garnets point to Georgian or Victorian work, calibre-cut sapphires point to Art Deco, and large, brightly colored synthetic rubies and sapphires point to Retro jewelry from the 1930s and 40s, when synthetics were used openly and deliberately even in fine pieces. Treatment is the other key question: almost all emeralds are oiled and most sapphires and rubies are heat-treated, both accepted trade practice, and what matters for value is disclosure rather than the treatment itself.
Colored stones carry more information about a piece's age than most buyers expect, because both the cutting style and the type of stone used shifted noticeably from one era to the next. A little familiarity with what was common when helps you judge whether a stone belongs in its setting.
It also helps you ask the right questions about treatment, since almost every colored stone on the market today, antique or modern, has been treated in some accepted way, and disclosure is what separates normal trade practice from a problem.
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Sapphires, emeralds and rubies by era
Georgian and Victorian jewelry favored foiled, closed-back settings for colored stones, which boosted color and brilliance before modern cutting could do it with facets alone; garnets, in particular, were cut flat with a closed back throughout this period. Edwardian jewelry brought sapphires into fashion in delicate, millegrain platinum settings, often paired with diamonds.
Art Deco jewelers used calibre-cut sapphires, rubies and emeralds extensively, shaped precisely to follow a curve or fill a channel with no gaps, a slow, skilled cutting technique that is itself a strong signal of period work. Retro jewelers of the 1930s and 40s moved toward large, saturated aquamarines, citrines, and both natural and openly synthetic rubies and sapphires, used more for bold color and scale than rarity.
- Georgian/Victorian: foiled, closed-back garnets and colored stones
- Edwardian: sapphires in fine millegrain platinum settings
- Art Deco: calibre-cut sapphires, rubies and emeralds set in tight channels
- Retro: large citrine, aquamarine, and natural or synthetic ruby and sapphire
Synthetics are not automatically fakes
Laboratory-grown, flame-fusion rubies and sapphires have been commercially available since roughly 1905 and were used openly in fine jewelry, including by major houses, prized for their consistent, saturated color in calibre-cut rows. A synthetic accent stone in a Retro or later piece is genuinely period-correct rather than a sign of dishonesty.
What makes the difference between honest period jewelry and a problem is disclosure. A reputable seller identifies natural versus synthetic stones and states it plainly in the description, since the two can look identical to the naked eye and only differ under laboratory examination.
“With colored stones, ask what has been done to it before you ask what it weighs.”
Treatments and what they mean for value
The great majority of emeralds on the market, antique or modern, are oiled to fill natural surface-reaching fractures and improve clarity, a treatment accepted throughout the trade as long as it is disclosed. Most sapphires and rubies are heat-treated to improve or stabilize their color, another long-accepted and widespread practice.
More aggressive treatments, such as glass filling of ruby fractures or diffusion treatments that add color only to a stone's surface layer, are a different matter and typically reduce a stone's value more significantly, since they can be less stable and are less accepted as standard practice. Ask specifically whether a stone has been treated beyond routine oiling or heating, and expect a straight answer.
Frequently asked questions
- Are synthetic stones in antique jewelry a problem?
- Not if they are disclosed and period-correct. Synthetic rubies and sapphires were used in fine jewelry from the early 1900s onward, especially in Retro pieces, and are a genuine part of the history of those designs rather than a later substitution.
- Is an oiled emerald considered damaged?
- No. Oiling to fill surface-reaching fractures is standard, widely accepted practice for the great majority of emeralds sold anywhere, antique or modern. It should be disclosed, but it does not indicate a flawed or dishonestly sold stone.
- How can I tell if a colored stone is period-correct for a piece?
- Look at the cutting style and setting technique alongside the stone type. Flat, foiled garnets suggest Georgian or Victorian work, calibre-cut stones suggest Art Deco, and large, boldly colored centers suggest Retro; a stone whose cut clearly postdates its mount suggests a later replacement.
Written by our estate jewelry team and reviewed by our in-house gemologist, a GIA Graduate Gemologist (GG). We have been buying and selling European antique jewelry since 1973.
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