Key properties
| Chemical formula | Ca5(PO4)3(F,OH,Cl) |
| Crystal system | Hexagonal |
| Mohs hardness | 5 |
| Toughness | Fair |
| Refractive index | 1.634-1.638 |
| Birefringence | 0.0020-0.0080 |
| Optic character | Uniaxial negative (-) |
| Dispersion | 0.0130 |
| Specific gravity | 3.13-3.23 |
| Cleavage | Poor to indistinct in two directions (basal and prismatic) |
| Fracture | Conchoidal to uneven |
| Habit | Hexagonal prisms with flat basal terminations (pointed pyramidal terminations are uncommon); also massive and granular |
| Lustre | Vitreous; polish: Vitreous |
| UV fluorescence | Varies with colour: yellow - purplish pink (stronger LW); blue - blue to light blue; green - greenish yellow (stronger LW); violet - greenish yellow LW, light purple SW; often weak to absent in cat's-eyes. |
| Pleochroism | Strong in blue (blue versus yellow to colourless); very weak to weak in other colours. |
| Cause of colour | Manganese-related centres colour the neon blue to blue-green Madagascan material; rare-earth elements (didymium - neodymium and praseodymium) colour yellow and green stones; pink is a fading colour centre. |
| Typical inclusions | Parallel rutile needles or growth tubes (cause chatoyancy), fingerprint-like healed fractures, colour zoning; strained crystals may show a pseudo-biaxial optic figure |
| Stability | Very heat sensitive - colour may fade or change; usually stable to light except some pink; attacked by sulfuric and hydrochloric acids |
| Heat sensitivity | Very high |
| Care and cleaning | Warm soapy water safe; ultrasonic risky; steam cleaner never |
| Availability | Scarce in fine grades; blue Madagascan material the trade staple |
| Recognition | RI around 1.63 with low birefringence, uniaxial negative figure, SG near 3.2 and hardness 5 (the Mohs 5 reference mineral - a pocket-knife edge scratches it), neon blue-green saturation plus a strong dichroscope reaction flags apatite immediately. |
Varieties (5)
Violet-Purple Apatite
| Colour | violet to purple |
| Transparency | transparent to translucent |
| Clarity type | Type II (typically included) |
| Phenomena | Rare chatoyancy |
| Appearance | Grape to lavender transparent gems with a velvety saturation; darker tones approach amethyst in look but with far softer durability. |
| Trade names | purple apatite |
| Misnomers | occasionally confused with scapolite or amethyst at the counter |
| Typical sizes | 1 to 10 ct |
| Cutting styles | Faceted in mixed cuts; calibrated small stones common |
| Key separations | vs amethyst: RI 1.63 vs 1.544-1.553, SG 3.2 vs 2.65, apatite is uniaxial negative with hardness 5; vs scapolite: scapolite is biaxial; vs tanzanite: tanzanite RI 1.69 with strong trichroism |
| Sources (localities) | Madagascar • Mozambique • Brazil • Sri Lanka |
| Availability | Scarce; usually seen as accent stones |
| Market notes | Moderately priced; attractive saturated purple with good clarity sells well |
| Care notes | Warm soapy water; no steam, ultrasonic risky; avoid heat |
| In short | Violet-purple apatite is a saturated but soft collector-designer stone, separated from amethyst in seconds by its higher RI and SG. |
| Size (ct) | USD per carat | Tier | As of |
|---|---|---|---|
| 1.00–5.00 | $15.00 – $70.00 | commercial to fine | 2026-10-26 |
| 5.00–10.00 | $25.00 – $90.00 | fine | 2026-10-26 |
Retail market survey, per carat unless noted. Ranges describe what commercial to fine stones trade at; exceptional stones and provenance premiums sit above them.
Blue Apatite (Madagascar)
| Colour | neon blue to blue-green |
| Transparency | transparent to translucent |
| Clarity type | Type II (typically included) |
| Phenomena | Chatoyancy in included material (cat's-eye apatite) |
| Appearance | Electric turquoise-blue that seems lit from within - the trade's 'neon' or 'swimming-pool' blue; softer, deeper tones resemble fine paraiba-like colour at a fraction of the price. |
| Trade names | neon blue apatite • Madagascan blue apatite • moroxite (old name for blue apatite) |
| Misnomers | sometimes marketed with paraiba tourmaline comparisons - it is not tourmaline |
| Typical sizes | 1 to 20 ct; clean stones above 5 ct scarce |
| Cutting styles | Faceted in mixed and step cuts; cabochons when chatoyant or included; must be oriented to show blue (not yellow) through the table |
| Key separations | vs blue topaz: topaz is biaxial positive with DR 0.008-0.010, SG 3.53; apatite uniaxial negative, DR usually 0.003, SG 3.2; vs indicolite tourmaline: tourmaline DR 0.014-0.032, SG 3.05, different pleochroism; vs zircon: zircon RI 1.92+ with high lustre |
| Sources (localities) | Madagascar (main neon blue) • Mozambique • Brazil • Sri Lanka |
| Availability | Steady supply of small calibrated stones; fine large gems scarce |
| Market notes | Popular designer stone; price sensitive to saturation ('neon') and clarity; demand spiked with the paraiba-look fashion |
| Care notes | Warm soapy water; ultrasonic risky; never steam; protect from heat and knocks in rings |
| In short | Madagascan blue apatite is the neon-blue bargain of the gem world: RI 1.63, strong blue/yellow dichroism and hardness 5. It demands protective settings but delivers remarkable colour per dollar. |
| Size (ct) | USD per carat | Tier | As of |
|---|---|---|---|
| 1.00–5.00 | $15.00 – $60.00 | commercial to fine | 2026-10-26 |
| 5.00–10.00 | $30.00 – $120.00 | fine | 2026-10-26 |
Retail market survey, per carat unless noted. Ranges describe what commercial to fine stones trade at; exceptional stones and provenance premiums sit above them.
Green Apatite
| Colour | yellowish green to green |
| Transparency | transparent to translucent |
| Clarity type | Type II (typically included) |
| Phenomena | Chatoyancy (green and yellow cat's-eyes are the trade standard) |
| Appearance | Fresh spring to olive green transparent gems; the translucent included material cuts attractive green cat's-eyes with a sharp silver eye. |
| Trade names | asparagus stone (yellowish green transparent) • green cat's-eye apatite |
| Misnomers | 'asparagus stone' is a trade name, not a separate species |
| Typical sizes | Faceted 1-20 ct; cat's-eye cabs 1-15 ct |
| Cutting styles | Faceted; cabochons for cat's-eyes |
| Key separations | vs peridot: peridot RI 1.65-1.69 with DR 0.035 and SG 3.34; vs green tourmaline: DR 0.014-0.032; vs chrome diopside: RI 1.67-1.70, SG 3.3 - all clearly above apatite's 1.63 and low birefringence |
| Sources (localities) | Kenya (cat's-eye) • Madagascar • Brazil • Mexico • Spain • Sri Lanka |
| Availability | Scarce as fine transparent gems; cat's-eye regularly available |
| Market notes | Green cat's-eye apatite is an affordable, attractive phenomenal stone; transparent green sells to collectors |
| Care notes | Warm soapy water; ultrasonic risky; never steam |
| In short | Green apatite spans transparent 'asparagus stone' to reliable green cat's-eyes, coloured by rare-earth elements. Low birefringence and hardness 5 set its limits and its identity. |
| Size (ct) | USD per carat | Tier | As of |
|---|---|---|---|
| 1.00–5.00 | $10.00 – $45.00 | commercial to fine | 2026-10-26 |
| 1.00–15.00 | $8.00 – $50.00 | commercial to fine | 2026-10-26 |
Retail market survey, per carat unless noted. Ranges describe what commercial to fine stones trade at; exceptional stones and provenance premiums sit above them.
Yellow Apatite
| Colour | yellow to yellowish brown |
| Transparency | transparent to translucent |
| Clarity type | Type II (typically included) |
| Phenomena | Chatoyancy in included stones (classic yellow cat's-eye) |
| Appearance | Sunny lemon to honey yellow transparent gems, sometimes with brown zoning; included rough cuts into the trade's familiar golden cat's-eye. |
| Trade names | yellow cat's-eye apatite • asparagus stone (greenish yellow) |
| Misnomers | none significant |
| Typical sizes | 1-20 ct faceted; cat's-eyes to 20+ ct |
| Cutting styles | Faceted; cabochons for cat's-eyes (oriented to the needle direction) |
| Key separations | vs citrine: RI 1.63 vs 1.544-1.553; vs golden topaz: topaz RI 1.61-1.64 (overlap!) - separate by optic sign (apatite uniaxial - vs topaz biaxial +), SG (3.2 vs 3.53) and spectrum (580 doublet); vs chrysoberyl: RI 1.74-1.75 |
| Sources (localities) | Mexico (Durango yellow) • Brazil • Tanzania (yellow cat's-eye) • Kenya • Sri Lanka |
| Availability | Steady for cat's-eye; transparent yellow scarce |
| Market notes | Yellow cat's-eye apatite is a jewellery-trade staple at gentle prices; faceted yellow is a collector item |
| Care notes | Warm soapy water; ultrasonic risky; never steam |
| In short | Yellow apatite supplies both bright faceted gems and the classic golden cat's-eye, identifiable by its 580 nm rare-earth doublet and uniaxial negative optic figure. |
| Size (ct) | USD per carat | Tier | As of |
|---|---|---|---|
| 1.00–10.00 | $8.00 – $40.00 | commercial to fine | 2026-10-26 |
| 10.00–20.00 | $10.00 – $50.00 | fine to collector | 2026-10-26 |
Retail market survey, per carat unless noted. Ranges describe what commercial to fine stones trade at; exceptional stones and provenance premiums sit above them.
Colourless Apatite
| Colour | colourless |
| Transparency | transparent |
| Clarity type | Type II (typically included) |
| Phenomena | Chatoyancy (colourless cat's-eyes occur) |
| Appearance | Water-clear, bright but dispersion-poor faceted stones of purely collector interest. |
| Trade names | colourless apatite |
| Misnomers | none |
| Typical sizes | 1-10 ct |
| Cutting styles | Faceted; cabochon when chatoyant |
| Key separations | vs colourless topaz: SG 3.2 vs 3.53 and optic sign; vs quartz: RI 1.63 vs 1.545; vs glass: apatite is DR with inclusions |
| Sources (localities) | Brazil • Myanmar • Mexico |
| Availability | Rare; collector material only |
| Market notes | Minimal; sold for reference collections |
| Care notes | Warm soapy water; no steam |
| In short | Colourless apatite is a scarce, low-value collector stone whose constants (RI 1.63, uniaxial negative, SG 3.2) make it a favourite identification exercise. |
| Size (ct) | USD per carat | Tier | As of |
|---|---|---|---|
| 1.00–10.00 | $5.00 – $30.00 | collector | 2026-10-26 |
Retail market survey, per carat unless noted. Ranges describe what commercial to fine stones trade at; exceptional stones and provenance premiums sit above them.
Sources
· mindat.org · Wikipedia
Data compiled and fact-checked against gemmological literature, October 2026 (JDMIS gem reference). Properties are ranges accepted in gemmological practice; individual stones vary.
See also
Gemstone reference entries: gem #11 · gem #45 · gem #74 · gem #112 · gem #165
Related materials: Corundum · Diamond · Opal · Quartz · Spinel · Topaz
Identification wizard · All 83 materials · Singapore gem labs