Guide Gemstone Density

Different types of gemstones vary in density, and this fact is of interest to both gemologists and consumers.

It is important for consumers to understand gemstone density because buying colored gems by carat weight alone can lead to unexpected results. Though it is common to buy diamonds by weight, colored gems vary greatly by density. For example, a 1 carat sapphire is significantly smaller than a 1 carat diamond, while a 1 carat opal is significantly larger.

In gemology, the density or specific gravity of a gemstone is computed as the ratio of the density of the material to the density of water. The density is expressed as a number which indicates how much heavier the gemstone is compared to an equal volume of water.

Most gemstone varieties are 2 to 4 times denser than a equal volume of water. But the range is quite wide -- from 8 for cinnabar to 1 for amber. Diamond, at 3.50 to 3.53, falls approximately in the middle.

	Gem Variety	Density	Chemical Composition
	Cinnabar	8.0-8.2	Mercury  sulfide
	Cassiterite	6.7-7.1	Tin oxide
	Cerussite	6.46-6.57	Lead  carbonate
	Scheelite	5.9-6.3	Calcium tungstate
	Cuprite	5.85-6.15	Copper oxide
	Hematite	5.12-5.28	Iron oxide
	Barite	4.43-4.46	Barium sulfate
	Spessartite Garnet	4.12-4.18	Manganese aluminum silicate
	Painite	4.01	Calcium  aluminum zirconium borate
	Smithsonite	4.00-4.65	Zinc carbonate
	Ruby	3.97-4.05	Aluminum oxide
	Star Ruby	3.97-4.05	Aluminum oxide
	Celestine	3.97-4.00	Strontium sulfate
	Sapphire	3.95-4.03	Aluminum oxide
	Star  Sapphire	3.95-4.03	Aluminum oxide
	Zircon	3.93-4.73	Zirconium silicate
	Almandine  Garnet	3.93-4.30	Iron aluminum silicate
	Sphalerite	3.90-4.10	Zinc sulphide
	Rhodolite  Garnet	3.84	Magnesium aluminum silicate
	Color-Change  Garnet	3.78-3.85	Complex aluminum silicate
	Malaia Garnet	3.78-3.85	Complex aluminum silicate
	Gaspeite	3.71	Nickel  magnesium iron carbonate
	Demantoid  Garnet	3.7-4.1	Calcium iron silicate
	Azurite	3.77-3.89	Basic copper carbonate
	Alexandrite	3.70-3.78	Beryllium aluminum oxide
	Alexandrite  Cat's Eye	3.70-3.78	Beryllium aluminum oxide
	Chrysoberyl	3.70-3.78	Beryllium aluminum oxide
	Chrysoberyl  Cat's Eye	3.70-3.78	Beryllium aluminum oxide
	Vanadium  Chrysoberyl	3.70-3.78	Beryllium aluminum oxide
	Mali Garnet	3.65	Calcium  aluminum silicate
	Benitoite	3.64-3.68	Barium titanium silicate
	Pyrope  Garnet	3.62-3.87	Magnesium aluminum silicate
	Taaffeite	3.60-3.62	Magnesium beryllium aluminum oxide
	Grossular  Garnet	3.56-3.73	Calcium aluminum silicate
	Hessonite Garnet	3.56-3.73	Calcium aluminum silicate
	Leuco Garnet	3.56-3.73	Calcium aluminum silicate
	Tsavorite  Garnet	3.56-3.73	Calcium aluminum silicate
	Spinel	3.54-3.63	Magnesium aluminum oxide
	Kyanite	3.53-3.70	Aluminum silicate
	Sphene  (Titanite)	3.52-3.54	Calcium titanium silicate
	Diamond	3.50-3.53	Carbon
	Imperial  Topaz	3.49-3.57	Aluminum fluosilicate
	Topaz	3.49-3.57	Aluminum fluosilicate
	Sinhalite	3.46-3.50	Magnesium aluminum borate
	Rhodochrosite	3.45-3.70	Manganese carbonate
	Serendibite	3.42-3.52	Complex borosilicate
	Uvarovite Garnet	3.41-3.52	Calcium chromium silicate
	Rhodonite	3.40-3.74	Manganese silicate
	Tanzanite	3.35	Calcium aluminum silicate
	Idocrase  (Vesuvianite)	3.32-3.47	Aluminum calcium silicate
	Epidote	3.3-3.5	Calcium aluminium iron sorosilicate
	Hemimorphite	3.30-3.50	Hydrous basic zinc siilcate
	Diaspore	3.30-3.39	Hydrated aluminum oxide
	Jadeite Jade	3.30-3.38	Sodium aluminum silicate
	Peridot	3.28-3.48	Magnesium iron silicate
	Dioptase	3.28-3.38	Copper cyclosilicate
	Jeremejevite	3.28-3.31	Aluminum borate
	Kornerupine	3.27-3.45	Magnesium aluminum borosilicate
	Dumortierite	3.28-3.41	Aluminum borate silicate
	Axinite	3.26-3.36	Calcium aluminium borosilicate
	Malachite	3.25-4.10	Basic copper carbonate
	Sillimanite	3.27-3.27	Aluminum silicate
	Chrome Diopside	3.22-3.38	Calcium magnesium silicate
	Diopside	3.22-3.38	Calcium magnesium silicate
	Enstatite	3.20-3.30	Magnesium silicate
	Apatite	3.16-3.23	Fluoro or chloro calcium phosphate
	Cat's Eye Apatite	3.16-3.23	Fluoro or chloro calcium  phosphate
	Zoisite	3.15-3.38	Calcium aluminum silicate
	Hiddenite	3.15-3.21	Lithium aluminum silicate
	Kunzite	3.15-3.21	Lithium aluminum silicate
	Spodumene	3.15-3.21	Lithium aluminum silicate
	Clinohumite	3.13-3.75	Magnesium silicate
	Euclase	3.10	Beryllium alum.  hydroxide silicate
	Andalusite	3.05-3.20	Aluminum silicate
	Actinolite	3.03-3.07	Basic calcium magnesium iron silicate
	Amblygonite	3.01-3.11	Lithium sodium aluminum flurophosphate
	Fluorite	3.00-3.28	Calcium fluoride
	Brazilianite	2.98-2.99	Sodium aluminum phosphate
	Danburite	2.97-3.03	Calcium boric silicate
	Grandidierite	2.97-3.03	Magnesium aluminum borosilicate
	Phenakite	2.95-2.97	Beryllium silicate
	Aragonite	2.94	Calcium carbonate
	Pezzotaite	2.90-3.10	Caesium beryllium lithium alum. silicate
	Nephrite Jade	2.90-3.03	Calcium aluminum iron silicate
	Datolite	2.90-3.00	Calcium boron hydroxide nesosilicate
	Chrome  Tourmaline	2.82-3.32	Soldium lithium boron silicate with chromium
	Paraiba  Tourmaline	2.82-3.32	Soldium lithium boron silicate with copper
	Rubellite  Tourmaline	2.82-3.32	Soldium lithium boron silicate
	Tourmaline	2.82-3.32	Soldium lithium boron silicate
	Prehnite	2.82-2.94	Basic calcium aluminum silicate
	Lepidolite	2.80-2.90	Potassium aluminum lithium silicate
	Sugilite	2.76-2.80	Pot. sodium lith. iron manganese alum. silicate
	Ammolite (Korite)	2.75-2.80	Calcium carbonate
	Eudialyte	2.74-2.98	Zirconium silicate
	Larimar (Pectolite)	2.74-2.88	Sodium calcium inosilicate hydroxide
	Calcite	2.69-2.71	Calcium carbonate
	Cobaltocalcite	2.69-2.71	Calcium carbonate & cobalt
	Aquamarine	2.68-2.74	Aluminum beryllium silicate
	Emerald	2.67-2.78	Aluminum beryllium silicate
	Golden Beryl	2.66-2.87	Aluminum beryllium silicate
	Goshenite  Beryl	2.66-2.87	Aluminum beryllium silicate
	Morganite	2.66-2.87	Aluminum beryllium silicate
	Red Beryl (Bixbite)	2.66-2.87	Aluminum beryllium silicate
	Labradorite	2.65-2.75	Sodium calcium aluminum silicate
	Andesine	2.65-2.69	Sodium calcium aluminum silicate
	Amethyst	2.65	Silicon dioxide
	Ametrine	2.65	Silicon dioxide
	Citrine	2.65	Silicon dioxide
	Rock Crystal	2.65	Silicon dioxide
	Rose  Quartz	2.65	Silicon dioxide
	Smoky  Quartz	2.65	Silicon dioxide
	Aventurine	2.64-2.69	Silicon dioxide
	Oligoclase	2.62-2.67	Sodium calcium aluminum silicate
	Sunstone	2.62-2.65	Sodium calcium aluminum  silicate
	Pearl	2.60-2.85	Calcium carbonate
	Coral	2.60-2.70	Calcium carbonate
	Agate	2.60-2.64	Silicon dioxide
	Jasper	2.58-2.91	Silicon dioxide
	Iolite	2.58-2.66	Magnesium aluminum silicate
	Bloodstone	2.58-2.64	Silicon dioxide
	Carnelian	2.58-2.64	Silicon dioxide
	Chalcedony	2.58-2.64	Silicon dioxide
	Chrome  Chalcedony	2.58-2.64	Silicon dioxide
	Chrysoprase	2.58-2.64	Silicon dioxide
	Gem Silica	2.58-2.64	Silicon dioxide
	Onyx	2.58-2.64	Silicon dioxide
	Scapolite	2.57-2.74	Sodium calcium aluminum silicate
	Moonstone	2.56-2.59	Potassium aluminum silicate
	Amazonite	2.56-2.58	Potassium aluminum silicate
	Orthoclase	2.56-.2.58	Potassium aluminum silicate
	Charoite	2.54-2.78	Complex alkaline calcic silicate
	Williamsite	2.51-2.63	Hydrous magnesium iron phyllosilicate
	Poudretteite	2.51-2.53	Potassium sodium boron silicate
	Lapis Lazuli	2.50-3.00	Sodim calcium aluminium silicate
	Howlite	2.45-2.58	Calcium borosilicate hydroxide
	Carletonite	2.45	Hydrated pot. sodium calcium carb. silicate
	Hauyne	2.40-2.50	Sodium  aluminum silicate
	Petalite	2.40	Lithium aluminium phyllosilicate
	Obsidian	2.35-2.60	Siliceous glassy rock
	Hambergite	2.35	Beryllium borate
	Moldavite	2.32-2.38	Silicon dioxide compound with other minerals
	Turquoise	2.31-2.84	Hydrated copper aluminum phosphate
	Hackmanite	2.14-2.40	Sodium aluminum  chloride silicate
	Sodalite	2.14-2.40	Sodium aluminum chloride silicate
	Chrysocolla	2.00-2.40	Hydrous copper silicate
	Mexican  Fire Opal	1.88-2.50	Hydrous silicon dioxide
	Opal	1.88-2.50	Hydrous silicon dioxide
	Ulexite	1.65-1.95	Hydrated sodium calcium borate hydroxide
	Jet	1.19-1.35	Carbon (bituminous coal)
	Amber	1.05-1.09	Fossilised  organic resin