Isotropic Anisotropic Unusual RI Single Double Uniaxial Source Chemical Formation properties Wearebility Refractive I Birefringence Optic R refractive Dichroic Character Fosiled resin from tree 50 will melt with Amber Baltic Sea mm Fosilized resin mill years old torch applied 1,540 none none pegmatite dikes as Sio2 Silicon hydrothermal uniaxial Amethyst Brazil oxide crystals very good 1.544-1.553 0,009 Positive U+ x x heat and pressure Calcium caused CaCO Carbonate, in the shell to CaCO as trasnform to Ammolite Canada aragonite aragonite Good N/A None none many, first gem gravels know Al2Si05, and secondary andalusia, Alumium deposits of biaxial Andalusite spain silicate clay. good, 7,5 1.633-1.648 0,007 negative B- x many Sri lanka, India, Madagascar, calcium Prismatic not so good, Uniaxial Apatite US & Mexico phosphate crystals soft 1.632-1.646 0,003 avg negative U- x x Mainly parts if copper deposit mainly as an in chile, aggregate with Russia, US, copper malachite in Biaxial positive Azurite France AU carbonate copper deposit none not good 1.730-1.838 0,108 B+ x Very small San Benito, prismatic Very Uniaxial Benitoite California BaTiSi3O9 crystals flourescense fairly well 1.757-1.804 0,047 average Positive U+ x x vast array of colors and forms as formations, SiO2, silicon millions of tiny and easy to Uniaxial Chalcedony anywhere oxide crystals dyed very good 1.530-1.539 0,006 Positive U+ x x higly unique massive rock coloration Charoite USSR formations pattern very good 1,550 +/- none none Chatoyancy(ca most from BeAlO2 is an In pegmatite t's eye) and Biaxial positive Chrysoberyl Brazil oxide dikes color change very good 1.746-1.755 0,008 +/- B+ x In hydrothermal SiO2 form of veins chalcedony associated Brazil, Russia, being a with nichel ore Uniaxial Chrysoprase India, S. Africa siliconoxide deposits very good 1.530-1.539 Positive U+ x x In hydrothermal most in Brazil, veins and but also US, SiO2, member pegmatite Uniaxial Citrine Russia, Spain of quartz family dikes very good 1.544-1.553 0,009 +/- Positive U+ x x pearls in the good for Only the warm gastropod pendants and waters of Concretion of Strombus Flame earrings, but Conch Pearl Caribbean conchiolin Gigas structure not hard varies none none USA, Mexico, Myanmar and Calcium boric biaxial Danburite other silicate none good 1.630-1.636 0,006 negative B- x crystallized 150 km deep the hardness, and brought to & driffract light surface very into spectral Diamonds many C (Carbon) fast by magna colors very good 2,410 isometric x The 4 rayed many, india, Calcium Occurs in star of star S.Africa, Italy, Magnesium prismatic diopside is Biaxial Diopside Austria Silicate crystals unique very good 1.671-1.726 0.28+/- Positive B+ x A varity including cat's eye and others. Best are colored by chromium, many, some are Columbia, Forms in colored by zambia, brazil, Hydrothermal vanadium and Uniaxial Emerald india BeAlSio2, vents are green beryl Good 1.577-1.583 0.005-0.009 Negative U- x x main is India, Occurs as but also Sri Magnesium prismatic Beutiful cat's Biaxial Enstatite Lanka and S.A Silicate crystals eye good 1.663-1.673 .01+/- Positive B+ x display of what member of the appears to be chalcedony burning Main is family of embers. Mexico, also Silicon Dioxide cryptocrystallin Always cut as Uniaxial Fire Agate e.g. Brazil (quartz) e quartz cabochon very good 1.530-1.540 .005+/- Positive U+ x x isotopic RI vaies from stone to stone. Pyrope 1.73- 1.76. Almindine 1.78-1.81. Spessartite 1.79-1.81. Grossular 1.73- Isomorphous In igneous 1.74 series rocks usually Demantoid replacement as Color change, 1.88. group. dodecahedral asterism and Uvarovite Garnet World Wide Solicates crystals chatoyancy very good 1.87+/- none none x Gaspe, Quebec, calcite group of In volcanic Uniaxial Gaspeite Canada minerals rock formation none very good 1.61-1.83 -0,22 Negative U- x x pegmatite Brazil, Aluminium dikes and Madgascar, beryllium granite Uniaxial Heliodore Nabibia mostly silicate formations none very good 1.577-1.600 0,016 Negative U- x x Pegmatite Mainly India, dikes and mix of red and Brazil, China, granite green and uniaxial Heliotrope US, Australia Silicon Dioxide formations yellow very good 1.530-1.539 .004+/- Positive U+ x x Vesuvius, complicated Russia, calcium 2 dschroic Canada US aluminium primary color Uniaxial Idocrase and others silicate igneous rocks Brown/green good 1.700-1.721 0.005+/- negative U- x x Pleochroism is extremely with one direction Mainly Brazil, Magnesium Primary of dark blue or Sri Lanka, Aluminium igneous rocks purple and one Biaxial Iolite India Silicate and pegmatites colorless good 1.530-1.550 .010 average Negative B- x metamorphic the color Sodium rock variety is the aluminum formations in most important Biaxial Jadeite Myanmar silicate the uru valley property extremely good 1.654-1.667 0,013 Positive B+ x mainly Greeland, also Magnesium Sri Lanka, aluminum Primary Biaxial Kornerupine Canada S.A. borate silicate Igneous Rock none very good 1.665-1.682 0,013 Negative B- x Mainly US, Lithium Brazil alumininum Pegmatite Biaxial Kunzite Madagascar silicate dikes none fair 1.660-1.680 0,016 Positive B+ x In metamorphic Mainly Nepal rock Forms in but also other Aluminum prismatic Biaxial Kyanite places silicate blades none fair 1.715-1.732 0,017 Negative B- x mainly Canada, also Sodium US, Mexico aluminum Labradorescen Biaxial Labradorite and Russia silicate Igneous rocks se very good 1.560-1.568 0,008 Positive B+ x best in West Hindues Kush Sulphur based in Afghanistan, rock with but also sodium Russia and aluminum Lapis Lazuli Chile silicate Igneous rocks none good 1,500 avg none none x mainly dominican Ignesious Larimar republic HNaCA2(Sio3) rocks none good 1.59-1.63 none none x A very unusual Republic og color scheme congo, with veins of australia, chile, Along veins of dark to light Biaxial Malachite US and others CU2(OH)2CO3 metamorphiccopper ore green fair to good 1.655-1.909 0,254 Negative B- x rock formed when higher pressure combination of changed minerals formation of Maw sit sit in including ignesious Maw Sit Sit myanmar jadeite rocks none good 1.52-1.54 N/A N/A al over most in generally small, Chech more than one republic, Impact melting 1 before australia and of host rock by cutting is rare Moldavite US Silicon Dioxide meteorites and expensive good 1.48-1.50 none none potassium Adularescence Sri lanka, aliminum igneous rocks or moonstone biaxial Moonstone Brazil and India silicate and formations effect good 1.520-1.525 0,005 negative B- x Brazil, Sri beryllium lanka and US aluminum In pegmatite Uniaxial Morganite (Cal) silicate formations none good 1.570-1.585 0.007+/- Negative U- x x decaying forest, but also in cavities in Australia, SiO2 with the rocks, Brazil, US H2O, solicon silicon form endless, every Opal (nevada) with water opal opal is unique fair 1.44-1.46 none none none, Rare to find with 0.036. One of most parts of Mg2Si=4, Primary chatoyancy or the largest to Biaxial positive Peridot the world Fe2Si=4 igneous rocks asterism good 1.654-1.690 find B+ x mainly Lithium Sodium None, Rare to australia and Aluminum Primary find Biaxial positive Petalite Brazil Silicate igneous rocks chatoyancy fair 1.502-1.518 0,016 B+ x Mainly Calcium None, Rare to Australia, Aluminum Primary find Biaxial positive Prehnite China Silicate igneous rocks chatoyancy good 1.61-1.64 0,03 B+ x Pegmatite dikes for large around the cuttable uniaxial Quartz world Silicon Dioxide crystals None good 1.544-1.553 0,009 Positive U+ x x pegmatite Thomas BeAlSiO2 dikes for large Mountains, colored by cuttable Uniaxial Red Beryl Utah US manganese crystals none good 1.570-1.579 0,009 Negative U- x x In stalamites due to silver depositionout of seeping water and in 0.22 one of Rhodochrosit Argentine and manganese primary extremen highest Uniaxial e US carbonate igneous rocks birefringence fair 1.600-1.820 existing Negative U- x x Mainly inprimary Sweden, US, igneous rocks Canada manganese as transparent Biaxial positive Rhodonite Australia S.A. silicate crystals none fair 1.733-1.744 0,011 B+ x Aluminium granite forming Burma, tha, oxide with lava intrude to Austr, Tanz, VN cronium for limestone Exelent. 2. On Uniaxial Ruby mm color marble Moh's scale 1.766-1.774 0,008 negative U- x x by contact metamorphism Many Paces, when granite e.g Maguk, forming lave Asterism, Burma, intrudes into chatoyance Thailan, Sri Aluminum limestone and other Uniaxial Sapphire Lanka Oxide marble things excellent 1.766-1.774 0,008 Negative U- x x Many, e.g. contact zone Maguk, Burma, igneous and (purple color Madagascar, pegmatite same RI as Uniaxial Scapolite Brazil very long formations chatoyancy fair 1.54-1.56 Amethyst) 0,02 Negative U- x x In metamorphic rocks usually rich in olivine, from which its magnesium get the color none due to Serpentine many places silicate green none fair 1.560-1.571 opaque nature none x As the protective Calcium dwelling places offer the same Carbonate(like of molluck and type of lustre pearls, same other water and orient than Shell world wide material) living creatures pearls good 1.52-1.56 0.014 avg none mainly Sri Lanka and Metamorphic Burma, but Magnesium contact zones also Russia aluminum iron in conjunction biaxial Sinhalite and US borate with limestone none fair to good 1.669-1.707 0,038 negative B- x (over Mainly Brazil Igneous rocks Extreme refractormeter Biaxial positive Sphene and Mexico Titanite formations dispersion/fire fair 1.885-2.050 limit) 0,105 B+ x Myanmar, Afghanistan, Magnesium Sri Lanka, Aluminum Igneous rock Spinel Brazil and US Oxide formations none very good 1,712 (can vary) none isometric x Igneous rock Uniaxial Sugilite S:A very long formations none very good 1.607-1.610 none Negative U- x x Complex Oregon US and sodium calcium India, Canada aluminum igneous rock Biaxial positive Sunstone Russia e.g.