The dealer laid three alexandrites on a white sorting cloth near the window. Daylight. All three appeared green. Different greens, the trained eye noticed, one pure, one slightly blue, one slightly olive. He picked up the first: a 1.8-carat oval, fine Brazilian, Gübelin certificate. Under the desk lamp, a rich purplish-red. Strong change. The second: 2.2 carats, certified India, moderate change. Under the lamp it went a brownish-red that was not quite convincing as red. The third: 1.2 carats, no certificate, labelled "Russian." Under the lamp, a vivid red, but more vivid than either of the others, a red with actual fire in it. He looked at the bottom of the label: no laboratory, no report number. "No certificate, no Russian," he said, putting it back. He explained it to the buyer: "The change on the uncertified stone looks good. Maybe it is Russian. But I've seen strong synthetic alexandrite that looked exactly like that. Without a Gübelin or an AGL, the word 'Russian' is a story, not a fact. The Brazilian with the Gübelin is a fact. You can sell a fact. Stories don't sell at Russian prices."
Quick answer: what are the five quality factors in alexandrite? Alexandrite has five primary quality factors: (1) strength of colour change, the completeness of the shift from green to red; (2) purity of colour in daylight, vivid, saturated green without grey, brown, or olive modification; (3) purity of colour in incandescent light, vivid, saturated red without brown or grey modification; (4) clarity, inclusions relative to Type II standards; (5) origin, verified Russian Ural commands the highest premium. All five must be assessed together. A stone with excellent change strength but heavily modified colour in one lighting condition is not a fine alexandrite. Sources: GIA Colored Stone assessment; Wise, R.W., Secrets of the Gem Trade (2016), pp. 142–152; Schmetzer, K., Russian Alexandrites (2010).

Factor 1: strength of colour change

Strength of colour change is the most distinctive quality variable in alexandrite. Unlike in other coloured stones where colour quality is assessed once, in a single lighting condition, alexandrite requires colour assessment twice and then a change-strength assessment for the transition between the two conditions.

The GIA and trade standard for colour change strength uses four grades: Weak (under 20% change), Moderate (20–50%), Strong (50–80%), Excellent (80–100%). The percentage represents the degree to which the daylight colour has been replaced by the incandescent colour, not literally a percentage measurement but a calibrated trade descriptor based on visual comparison (GIA Colored Stone assessment; Wise, 2016).

In practical terms: Weak means the stone looks greenish in incandescent light, not red. Moderate means a clear change is visible but the stone in incandescent light still looks somewhat greenish or brownish. Strong means the change is dramatic and unmistakable. Excellent means the change is complete: the stone appears fully red in incandescent light with no residual green visible to the eye.

Factor 2 and 3: colour purity in both conditions

The colour in each lighting condition must be evaluated independently for hue, tone, and saturation, then for the presence of modifying colours (grey, brown, olive, purple) that reduce the commercial quality.

Alexandrite colour quality: what to look for in each lighting condition Daylight assessment Fine: Pure, vivid, saturated green Good: Slightly blue-green modifier acceptable Commercial: Teal, blue-green with modifier Avoid: Olive, grey, brown modifier Best tone: medium to medium-dark Washed out (pale) = weak saturation Near-black = too dark; lose the green Incandescent assessment Fine: Pure vivid red, purplish-red Good: Raspberry red; slight purple modifier Commercial: Purplish, moderate brown Avoid: Heavy brown; brownish-red without red Test under true incandescent bulb LED warm-white insufficient Candlelight works; matches incandescent Source: GIA Colored Stone assessment; Wise, Secrets of the Gem Trade (2016). A fine alexandrite must score well in BOTH conditions independently.

Alexandrite colour quality assessment requires independent evaluation in both daylight and incandescent lighting. A stone that is vivid green in daylight but brownish-red (not truly red) in incandescent light is not a fine alexandrite regardless of change strength. Source: GIA; Wise (2016).

Factor 4: clarity in a Type II gem

Chrysoberyl is a GIA Type II gemstone for clarity: inclusions are present in some natural stones but not in all, and eye-clean material is available at commercial scale. This places alexandrite between Type I (mostly clean) and Type III (always included) on the clarity spectrum. Eye-clean alexandrite at fine quality is attainable and is the standard for premium commercial material; heavily included stones command significant discounts (GIA Gem Reference Guide, 2006, pp. 28–30; GIA Colored Stone).

The inclusions characteristic of alexandrite vary by origin. Russian Ural alexandrite often contains silk (rutile needles) and mineral crystal inclusions. Brazilian material has its own inclusion populations. Indian material is commonly more heavily included at commercial grade. For investment-grade alexandrite, particularly Russian material at significant sizes, eye-clean clarity is important; a stone with obvious face-up inclusions at a claimed Russian origin price point has reduced commercial appeal regardless of colour change quality (GIA; AGL; Schmetzer, 2010).

Factor 5: size premiums in alexandrite

The size premium in fine alexandrite is among the most dramatic of any coloured gem. Fine natural alexandrite above 1 carat with strong change is genuinely rare. Above 2 carats, it is rare by any objective standard. Above 5 carats with strong, pure colour change and clean clarity, it is among the rarest faceted gems in commercial production.

The non-linear price escalation for fine alexandrite:

SizeRussian fine, per caratBrazilian strong change, per carat
Under 0.5ctUSD 5,000–20,000USD 500–3,000
0.5–1ctUSD 15,000–60,000USD 2,000–8,000
1–2ctUSD 40,000–150,000USD 5,000–20,000
2–5ctUSD 80,000–300,000+USD 10,000–40,000
5ct+USD 200,000–1,000,000+USD 25,000–100,000

Approximate ranges, 2024–2025. Vary significantly by specific colour quality, change strength, clarity, and transaction context. Sources: Christie's Geneva; Sotheby's Geneva published results; AGL; Wise (2016); dealer benchmarks. These are approximations, not price guarantees. This is not investment advice.

The investment case for alexandrite

Russian Ural alexandrite has the structural investment case most similar to Kashmir sapphire among all coloured gems: an exhausted deposit with no new fine production, a documented appreciation trend at major international auction houses over two decades, and a buyer pool that has expanded significantly as Asian collector markets matured. The per-carat prices achieved at Christie's and Sotheby's Geneva for certified Russian alexandrite have increased by a factor of five to ten between 2000 and 2025 for the finest material (Christie's; Sotheby's published results; Schmetzer, 2010).

The practical barriers mirror those of any fine coloured stone investment: liquidity is low, transaction costs at auction are 25–40% round-trip, holding periods should be ten years or more, and authentication requires a current major laboratory certificate. Fine Russian alexandrite without a Gübelin, AGL, or GIA origin certificate cannot be sold at Russian premium prices at a major auction house. Re-certification before consignment is effectively required (Christie's; Sotheby's; AGL). This is not investment advice. Consult a qualified financial adviser before making investment decisions involving gemstones.

Synthetic alexandrite detection: what a laboratory confirms

Synthetic alexandrite is produced commercially and presents a significant fraud risk in all market tiers. The detection methodology:

Natural vs synthetic alexandrite: diagnostic features under microscope Feature Natural alexandrite Synthetic (Czochralski/flux) Growth structures Straight/angular growth zones Curved striae (Czochralski) Mineral inclusions Rutile silk, mineral crystals, fingerprints Flux veils, gas bubbles (no mineral crystals) Change strength Varies by origin; rarely perfect Often very strong/pure; "too good" UV fluorescence (LW) Variable by origin Often diagnostic fluorescence pattern Source: Nassau, K., Gems Made by Man (1980); GIA Colored Stone identification; Schmetzer (2010). Curved striae = definitive synthetic; trained gemologist identifies in minutes.

Natural vs synthetic alexandrite under microscope. Curved striae in Czochralski-grown synthetic is the primary definitive indicator. Natural material shows straight or angular growth zones and natural mineral inclusion populations. Source: Nassau (1980); GIA; Schmetzer (2010).

The practical implication for buyers: if an alexandrite shows "too good" colour change, stronger, cleaner, and more vivid in both lighting conditions than the origin claimed would typically produce, this is a reason for increased scrutiny, not increased confidence. Some of the most convincing synthetic alexandrites sold in the market are exactly the stones that appear finest on casual examination. Only a major laboratory certificate distinguishes them from natural.

Price reference across quality tiers (2024–2025)

Quality descriptionChange strengthOriginApprox. USD per caratIndian Rs equivalent
Finest vivid, 2ct+, pure green/redExcellentRussia, Gübelin/AGL certUSD 80,000–300,000+Rs 70,00,000–2,50,00,000+
Fine, 1–2ct, vivid, cleanStrongRussia, major certUSD 40,000–100,000Rs 35,00,000–85,00,000
Fine, 1–3ctStrongBrazil, GIA/AGL certUSD 8,000–30,000Rs 7,00,000–25,00,000
Good commercial, 1ctModerateBrazil or Tanzania, certUSD 2,000–8,000Rs 1,70,000–7,00,000
Commercial qualityWeak to moderateIndia, GIA India certUSD 200–2,000Rs 17,000–1,70,000
Uncertified commercialUnknownUnknown/IndiaUSD 20–200Rs 1,700–17,000

Approximate ranges, 2024–2025. Indian Rs figures calculated at approximately Rs 85/USD. Actual prices depend on specific quality, cut, size, and transaction context. Sources: Christie's; Sotheby's Geneva; AGL; dealer benchmarks. Not investment advice or price guarantees.

Frequently asked questions

I have an alexandrite that looks vivid green in daylight and vivid red by candlelight. Is it Russian?

Not necessarily. Strong, pure colour change occurs in fine Brazilian, fine Tanzanian, and occasionally fine Indian alexandrite. Synthetic alexandrite from Czochralski growth also shows very strong, pure colour change, sometimes stronger and purer than most natural material. The specific colour direction (Russian is typically pure green, not blue-green, in daylight; Russian red is pure red, not significantly purplish) is one indicator. But the only reliable answer is a major laboratory certificate from Gübelin, AGL, GIA, or SSEF with origin determination. Vivid colour change is a necessary but not sufficient condition for Russian origin.

What is the smallest alexandrite worth buying?

For Jyotish purposes, practitioners often specify minimum weights of 1–3 carats. For aesthetic jewellery, smaller alexandrites show the colour change effectively if the change is strong. For investment, stones below 0.5 carats are not individually significant enough for the auction market regardless of quality. For a collector wanting a genuine, documented fine alexandrite without a large budget, a certified 0.3–0.5ct Brazilian or Tanzanian stone with strong change and a major laboratory certificate is a legitimate acquisition.

Does alexandrite need to be treated?

Natural alexandrite does not require or typically receive the treatments that are routine in ruby (heating), sapphire (heating), or emerald (oiling). Chromium-coloured chrysoberyl's colour is stable and does not respond to the heating treatments that change corundum colour. There are no standard treatments for alexandrite; any treatment applied (coatings, impregnation) is considered non-standard and must be disclosed. Synthetic alexandrite may be sold without disclosure. The treatment question for alexandrite is: is it natural or synthetic? That is what a certificate confirms.

How do I test alexandrite at home before buying?

The basic two-step test: (1) Hold the stone near a north-facing window in natural daylight and assess the colour (should be green or blue-green, not brownish or olive). (2) Hold the stone under a true incandescent bulb (tungsten filament, not LED, not fluorescent) and assess whether it changes colour (should change clearly toward red or purplish-red). The result tells you whether a colour change is occurring and roughly how strong it is. It does not tell you whether the stone is natural or synthetic. A synthetic alexandrite with vivid change will pass this test easily. The home test eliminates clearly misrepresented stones (no change at all, meaning it is not alexandrite) but cannot substitute for laboratory confirmation of natural status or origin.

Sources cited in this article

  • GIA Gem Reference Guide. (2006). Gemological Institute of America. (pp. 54–57)
  • GIA Colored Stone assessment methodology. gia.edu.
  • Wise, R.W. (2016). Secrets of the Gem Trade (2nd ed.). Brunswick House Press. (pp. 141–152)
  • Schmetzer, K. (2010). Russian Alexandrites. Schweizerbart Science Publishers, Stuttgart.
  • Nassau, K. (1980). Gems Made by Man. Chilton Book Company.
  • AGL. Alexandrite quality grading and synthetic detection. aglgemlab.com.
  • Gübelin Gem Lab. Alexandrite certification. gubelingem.com.
  • Christie's Geneva. Published auction results for alexandrite. christies.com.
  • Sotheby's Geneva. Published auction results for alexandrite. sothebys.com.