There are more than 2000 minerals out of this only 90 minerals have quality of gem stones.

1) NATURAL
It can be identified only by checking the refractory index reading and by observing the inclusions like negative crystals, rutile needles,finger prints , hexagonal zoning (only not for ruby) etc.

2)  NATURAL HEAT TREATED OR OILED
Inclusions like descoid fracture,negative crystals, rutile needles,finger prints , hexagonal zoning (only not for ruby) etc. coloured and heat treated or oiled but not all the natural stones are coloured,heat treated or oiled.

3)  SYNTHETIC
Cultured in the lab , the chemical composition and hardness will be same but inclusions will be artificial looking like natural, with microscrope of min 60x inclusions of natural and synthetic can be differentiated) synthetic will have inclusions like flex grown,lining effect, gas bubbles, curved sripes,metals(copper/platinum/gold etc).

4) ORGANIC GEMS
Material produced by biological process whether animal or vegitable, pearl,coral,ivory,amber,their hardness is very low.

5) SIMULANTS
glass/plastic/imitations etc( can be detected by the dropping sound and by feeling with the teeth). (PHENOMENA-chatoyancy effect,asterism effect and other different effects on stones./ RI= REFRACTORY INDEX (ri reading is measured in refractory index meter) given below are the 25 gem stones families consisting their chemical composition , hardness, density, refractory indexes, originated in which country etc, and the stones belonging to these families.

1) CORUNDUM
Chemical composition=AL203/hardness=9/ density=4.0g/cm cube/ ri=1.77/1.76 -red colour.

1) Burma ruby-mogok region of burma (blood red colour to pale colour).
Thailand ruby-natural heat treated (dark red to brownish red).
Srilankan ruby-natural(light to very light red or purplish red).
African ruby-natural(purplish red/pigeon blood red.
Star ruby-natural(ruby colour or brownish/too pale or too purple with a distinct asterism).

2) Kashmir Sapphire natural-blue variety of corundum(violetish blue not very transparant).
burma/thai sapphire-rich/royal blue/dark blue/blue black.
srilankan sapphire-pale greyish blue/ligh blue/violet.
montana sapphire-steel/electric blue/higher metallic lustre.
african sapphire-pale blue/blue violet/red violet/pale yellow or alexandrite colour.
pink sapphire-pink sapphire and ruby looks very identical only difference is the depth in colour synthetic is produced.comes from srilanka.
violet sapphire- comes from srilanka and thailand.
yellow sapphire- comes from srilanka and burma.
green sapphire- comes from australia/montana usa/thailand.
colourless sapphire- used as substitute for diamonds but easily distinguished.comes from Srilanka.

3) Padparadscha Sapphire
Padparadscha Sapphire is a special variety of gem corundum, featuring a delicate color that is a mixture of pink and orange a marriage between ruby and yellow sapphire. Today, padparadscha is narrowly defined by Western gemologists as a Sri Lankan sapphire of delicate pinkish orange color. But the original use of the term was somewhat different.

2) CHRYSOBERYL(LASANAYA)BEAL2O4
golden colour and famous for catseye and alexandrite.
1)alexandrite-discovered on the birthday of alexander 2 the czar of russia in 1830. with phenomina.distinct change in colour called metamerism .green in daylight and red in incandescent light.

2)cats eye-colour greenish or brownish yellow same as honey.a narrowed pupil in the eye of the cat. phenomina and chatoyant effect.

3)chrysoberyl-colour yellow/green/greenish yellow/brownish yellow/pale yellow/ same colour range as cats eye. found in brazil, srilanka,madagascar.

3) SPINEL-MGAL2O4/RI-1.74/SI/HARDNES-8/-COLOUR-RED
same colour as ruby ,duplicated as ruby, found in afganistan,india,burma,srilanka,brazil.
1)blue spinal-bright blue colour looks like sapphires.

4)  TOPAZ
Silicate of aluminium containing flouride and hydroxyl- ri-1.61 to 1.64/ hardness-8. synthetic/yellow is the main colour/brazilian topaz is famous/found in mexico/us/srilanka/japan/with very less inclusions.

1)pink topaz-comes mainly from brazil.
2)blue topaz-comes mainly from brazil,mexico,us.
3)colourless topaz-colourless / comes mainly from brazil,us, russia,germany,japan,africa.

5) BERYL
Silicate of beryllium and aluminium/ri-1.56 to 1.60 /hardness-7.5 to 8/opaque/milky white or faint yellow colour/comes from all over europe, america,south africa,himalayan asia. emerald-green variety of beryl but all green beryls are not emeralds/all emeralds have inclusions like bubble of gas/ cavities/cracks/oil treated/colour treated.

1)columbian emerald-slightly yellowish or bluish green/best are from muzo/chivor mines.
russian or siberian emeralds-more yellowish green/natural/treated.
brazilian emeralds-
sundawana emeralds-
zambian emeralds-

2)aquamarine-watery green,rich sky blue/free of inclusions/comes from brazil/available in 10 of carats/it is imitated by blue glass.

3)morganite-pink variety of beryl is named as morganite after the famous american banker/found in california,brazil,madagaskar.

4)golden beryl-brownish yellow colour.

5)heliodo-yellow green of olive oil ,yellow to brown colour, found in madagascar and brazil, no synthetics.
6)red beryl or bixbite-ruby red colour of beryl.

7)cats eye beryl-chatoyancy sometimes occurs in semi transparent beryl if it is cut as cabochons to bring out catseye effect,but is not as good as chrysoberyl cats eye.

8)star beryl-indark yellow brown to black beryl a poor star is seen, it is sometime confused with black star sapphire.

6) PYROPE-ALMANDINE GARNET-FEMG3/ AL2SL3O12
silicate of magnesium, iron and aluminium belonging to the garnet family.

1)pyrope-substitute of ruby,bright red colour,perfectly transparent found in brazil,tanzania,usa,mexico,argentina,australia ,usually inseveral hundred carats. no synthetics.

2)rhodolite/si/ri-1.755 to 1.765/density-3.75 to 3.94gm/cm3-deep pink or pinkish colour,good transparency,found in usa,zimbabwe,tanzania,srilanka.no synthetics.

3)almandine-si/red to deep violet red colour found in srilanka/india/burma/brazil/us/madagascar/tanzania/australia.

7) SPESSARTITE GARNET(SPESSARTINE)-MN3AL2SI3O12
Silicate of manganese and aluminium from garnet family from the spessart region of west germany, orange pink,orange red, brownish yellow,opaque or transparent, found in us ,mexico,west germany,mdagascar, mexico.

1)spessartine-orange red,orange pink colour ,good transparency.

8) GROSSULAR GARNET-CA3AL2SI3O12
Silicate of calcium and aluminium ,some of the crystals resembles gooseberry.greeenish to yellowish varities used as gems,.srilanka,us,canada,mexico,madagascar,kenya,tanzania.

1)hessonite-yellow brown varety of grossular is hessonite,found in srilanka,us,canada,brazil.

2)green grossular-light or dark green similar to green tourmalines and resembles african emerald,.found in kenya,tanzania and pakistan.

9) ANDRADITE-CA3FE2SI3O12
Silicate of calcium and iron belonging to garnet group-found in soviet union,us,norway,germany. colour varies due to slight variation in the chemical composition.

1)demantoid-pale to clear green variety of andradite garnet,good transparency,found in soviet union.

10) ZIRCON
Silicate of zirconium contain thorium and uranium/density-14.7g/cm3/ri-1.96to 2.01,colour is green,blue,greenish blue or colourless.edges will be brittle so it will be slightly damaged.

1)colourless zircon-cheap imitation to diamonds capable to deceive anyone for diamonds found in srilanka.no synthetics.

2)blue zircon- colour is obtained by heating treatment of other colour zircons-comes from cambodia,vietnam,thailand.

3)red zircon-brick or orange red ,si, comes from srilanka, cambodia, thailand.

4)yellow zircon-pale yellow,gold or greenish yellow,comes from srilanka,cambodia.

5)brown zircon-colour black tea to reddish brown tobacco or yellowish brown ,cheaper than other zircons.

6)green zircon-brownish green to yellow green, comes from srilanka,burma, value is very cheaper.

11) TOURMALINE-(NACA)(LI,AL,MG,FE,MN)3 (AL,FE)6 B3SI6O27(0,OH,F)4
Complex of borosilicate of aluminium and alkali with iron,magnesium and other cations.-color will be black,pink ,violet , brownish yellow,blackish brown,green,light blue,blue green, dark blue,comes from srilanka, soviet union, afghanistan,burma,us,brazil. no synthetics.

1)rubellite- pink to red colour tourmalines are called rubellite,cabochons when it is full inclusions, faceted oval, round, pear shaped, found in siberia,burma,srilanka,brazil,us,madagascar.

2)indicolite-greenish blue colour,found in brazil,us,madagaskar, soviet union. no synthetics.

3)green tourmaline-it is well known as rubellite and indicolitr,looks like african emeralds, colour is leaf green deep olive green,found in brazil,us,tanzania,mozambique, namibia,soviet union, no synthetics.

12) CORDIERITE-(mg,fe)2 al4 si5 o 18
Silicate of aluminium and magnesium,looks like blue sapphire,colour is grey,light or dark blue found in germany, norway,finland, brazil ,madagascar.no synthetics.

1)cordierite(water sapphire),colour grayish, warmer colour hint of violet, found in srilanka,us, namibia.no synthetics.

13) QUARTZ(sio2)
Silicon di oxide,very common mineral, no snthetics only natural.found in swiss alps,us,madagascar.

1)amethyst-violet ,purple to pink variety of quartz is amethyst,.found in us,madagascar, soviet union,india,australia,south africa,synthesized for different colour.

2)citrine quartz-yellow variety of quartz is citrine quartz,found i us, brazil, us soviet union. synthesized.

3)rose quartz-pink variety of quartz, only natural and imitation,found in brazil,us, madagascar.

4)colourless quartz-looks like crystal or ice or glass but the hardness of quartz is 7 and of lead glass is 5, value very low used for carving purpose found in brazil,madagascar.

5)tiger eye, hawk eye, bulls eye quartz-cut in cabochon to bring out chatoyancy, used for jewellery also for carving , no synthetics /colour bluishground called hawks eye/golden yellow ground called tigers eye/mahogany coloured ground called bulls or oxe eye.

6)aventurine-called indian jade,color bright green,grayish white overall appearence of jadeite, cut into necklaces ,pendents ,comes from india, soviet union, brazil.

7)chalcodany(haquie)-colour red or green.only natural.

14) JADEITE -naAISi206
Silicate of sodium and aluminium,colour brown,yellowish brown, orange yellow, reddish orange,lilac,hardness-6.5 to 7,ri-1.655to 1.667, density-3.3 to 3.4g/cm3,believed to be having therapeutic action for kidney diseases.comes from burma.

1)jadeite jade-semi opaque translucent emerald green yellow,greyish blue,pink etc, many different shades of green, used in making chinese arts.

15) SPODUMENE-lialsi2o6
Silicate of lithium and aluminium-colour is greyish white or ash grey,hardness-6to7,density is 3.1 to 7 /3.23g/cm3, ri-1.654to 1.679 this stone is similar to jadeite.trichoism and birefringence is seen.found in us, brazil,madagascar.

1)kunzite-violet pink transparent variety of spodumene,with pleochroism each stone will be 200 ct. found in us,brazil and madagascar.

2)hiddenite-green variety of spodumene,may resemble pale and strong coloured emeralds.

15) OLIVINE(PERIDOT)-(mgfe)2sio4
Silicate of magnesium and iron ,hardness-6.5 to 7,density is 3.32 to 3.35g/cm3,ri-1.654 to 1.690,colour is yellowish green,pale yellow tinged with green,with strong birefringerence found in us burma, italy, germany.

1)peridot,olivine,chrysolite- found in us,hawai,burma,brazil.
peridot-green colour
olivine-olive green colour
chrysolite-yellow colour

16) HEMATITE(fe2o3)
Colour dark blackish grey,non transparent found in uk,switzerland,germany, used as gem purposes for jewellery.

17) PYRITE)(fes2)
Iron sulphide produces spark if struck with iron,colour brassy yellow pale gold opaque,hardness-6to 6.5,density-5to 5.2g/cm3,confused with gold,called as fools gold.

18) OPAL(sio2nh2o)
Nonchrystalline hydrous silicon dioxide, chrystal system-nonchrystalline,1 to 2% water content,colour is light grey pale green,sky blue,smoke gray,black,yellowish,to orange or reddish background colour.hardness-5.5 to 6.5, density-1.98to 2.2g/cm3 ,ri-1.44 to 1.46, it is single ri,comes from australia,mexico,the range of colour varies in the patched due to diffraction.

1)white precious opal- color is whitish,dull yellow,light blue,pale blue,diffraction happens,found in chek,australia, mexico..

2)black opal-colour is bluish grey smoke grey to black,harlequin opal is most costly found mainly in australia and very less in indonesia,next after the principle 4 gem stones diamond,emerald, ruby, sapphire.synthetics are there but very expensive.have iridescence.

3)common opal-translucent, cloudy. without iridescence,

4) fire opal-colour is yellow to orange transparent have iridescence.comes from mexico,gautimala,us and australia.

5)noble orthoclase-colour varies from mid to golden yellow,transparent,common cut is step cut,no synthetics,comes from madagascar.

6)adularia moon stone-almost transparent ground colour is colourless or pale grey, tinged with yellow comes from srilanka,burma,india,australia, us ,brazil.

19) PLAGIOCLASE FELDSPARS-NAAISI3O8-CAAI2SI2O3
Silicate of sodium amd aluminium to silicate of calcium and aluminium,colour is white,grey,yellow,pale green ,transparent ,fully opaque,variety used in gems are albite(transparent)and labrodorite which is iridescent, hardness-6-6.5, ri-1.525 to 1.588comes from norway, soviet union, us.

1)albite moonstone-whitish colour,misty semi transparent density-2.62 to 2.65g/cm3, ri-1.525 to 1.536 with strong bifringence.

2)labradorite-dark smokey grey when light strikes changes into (blue to violet/striking rainbow coloured reflections)comes from canada,kenya,india,srilanka.

20) ZOISITE-CA2AL3SI3O12OH
Silicate of calcium and aluminium,colour is white,grayish,greenish,pink,blue ,bright green,prismatic cleavage,hardness-6.5, density-3.11 to 3.4g/cm3,ri are 1.69 to 1.7. found in east africa,norway.

1)tanzanite(blue zoisite)-colour is blue with violet tinge,pleochroism,different ri,mistaken with sapphire,found in tanzania.

21) NEPHRITE(CA2(MG,FE)5SI88O22(OH02)
Silicate of calcium,magnesium and iron,hardness-5 to 6,density-2,9 to 3.4g/cm3,ri-1.606 to 1.632,colour is whitish darkish green ,grey. found in soviet union,newzealand.

1)nephrite jade-colour is dark green to black grey or blue grey, used for artifacts jewellery,found in soviet union,newzealand,canada,us,australia.believed as effective in the treatment of kidney,ri-1.53, density-2.65g/cm3.

22) RHODONITE-MNSIO3
Silicate of manganese,colour is pink,flesh red,brownish red ,hardness-5.5 to 6.5,density-3.4 to 3.7g/cm3 ri-1.733 ,1.744,1.716 found in uk soviet,india,australia, south africa,mexico.

1)rhodonite-tranlucent to semi opaque,reddish pink come from found in uk soviet,india,australia, south africa,mexico.

23) DIOPSIDE-MGCASI2O6
Silicate of calcium and megnesium colour is bottle green to blackish green ,yellowish green,semi opaque,hardness-5.5 to 6,density-3.27 to 3.31g/cm3 ri-1.671,1.702,1.726 found in south africa,burma, srilanka,madagascar , brazil.

1)diopside-transparent greenish colour.comes from south africa,burma, srilanka,madagascar , brazil.

2)star diopside-displays asterism when cut star have 4rays where as 6 of other star varieties colour is blacish or blackish green

24) TURQUOISE-CUAL6(PO4)4(OH)85H2O
Hydrated phosphate of copper and aluminium- it is a non transparent gem,colour is blue white to sky blue, light greenish blue to light green,opaque only thin pieces are transparent,density-2.65 to 2.9g/cm3, ri-1.61,1.65,found in iran(best),us. no synthetics.

25) LAZURITE(lapis lazuli)-(NALCA)5(AL,SI)1 2024(5041 SN)
Silicate of sodium and aluminium containing sulphur,-colour is dull violet,hardness-5 to 5.5,density -2.38 -2.45g/cm3, ri-1.50,found in afghanistan and chile,us,canada,burma,angola.

1)lapis lazuli-semiopaque or opaque,dencity-2.7 to 3g/cm3,used for jewels,carved artifacts, vases.colour uniform colour without violet tinge is the costiliest.

ORGANIC GEMS
Material produced by biological process whether animal or vegitable, pearl,coral,ivory,amber,their hardness is very low,

1) PEARLS

1) Pearl cultured
Consist of 92%calcium carbonate and 6%conchilolin substance,pear egg or bean shaped,colour white grey to yellowish grey white,also blackish or grey to green blue violet and pink, pink is very rare, concentric layers of onion like structures,hardness-2.5 to 4.5,density-2.73 to 2.78,can be harvested between 5 to 7 years better result come up to 12 years, comes from srilanka,philippines,china,japan,australia,persian gulf,red sea.

2) Natural pearls
Colour white with a hint of gray or yellow, pink. shape is almost spherical,artificial nucleas will be inside.density is less than cultured pearl 2.71, grey natural pearl density is 2.61.

3) Cultured pearl
More spherical than the natural ones,comes from japan,china,india,grey colour,size of australian 10 to15 mm in diameter.
4)no nucleated cultured pearls-known as fresh water pearls,egg shaped,no artificial nucleus inside, size is not more than a gran of rice.

2) CORAL
Calcium carbonate in the form of calcite,they are skeletons of marine organsms,colour will be red ,orange ,pink,white,blue,black,comes from china,vetnam,japan,philippines and us.

3) AMBER
Fossil resin of trees that live tens of million years ago now extinct,transparent to semi opaque, colour is yellow to honey brown or reddish brown,found in soviet,poland,europe,poland,burma,africa.no synthetics only imitation(plastic).

4) IVORY-CA5(F,OH,CI)(PO4)3
Calcium phosphate in the form of oxyapatite and calcium phosphate and calcium carbonate with organic substance,tusks of elephants or teeth of hippo,walrus,no synthetics only imitation.