Frequently Asked Questions

1) Which all gemstones form the Navratnas?
1) Diamond (Vajram)
2) Ruby (Manikyam)
3) Sapphire (Indraneelam)
4) Yellow Sapphire (Manjapushyaragam)
5) Chrysoberyl cat's eye (Vaiduryam)
6) Emerald (Marathakam)
7) Hessonite Garnet (Gomedakam)
8) Pearl (Muthu)
9) Red Coral (Pavizham)

2) What is American diamond?
American Diamond is a man made material called Synthetic Cubic Zirconia with a chemical composition ZrO(Zirconium oxide). It is commonly used as a diamond simulant. Its dispersion value is higher than that of diamond. It can be easily distinguished from diamond.

Properties Diamond Synthetic Cubic Zirconia
Hardness 10 8 - 8.5
Specific Gravity 3.52 5.8 - 6.2
Refractive index 2.42 2.15
Dispersion 0.044 0.060

3) What are the factors that can affect the prices of natural gemstones?
1) Colour
2) Clarity
3) Cutting style
4) Carat weight or stone size
5) Treatments done on the stone
6) Distinctness of Phenomena (chatoyancy, aventurescence, asterism, change of colour etc.)
7) Place of origin

4) What are synthetic gemstones? What are the commonly encountered synthetic stones?
Synthetic gemstones correspond to their naturally occurring counterparts in crystal structure, physical, chemical and optical properties. Usually natural stones are distinguished from synthetic stones with the help of inclusions present. Some of the stones that are synthetically produced are:
Synthetic Emerald, Synthetic Chrysoberyl, Synthetic Beryl (red, yellow, blue)
Synthetic Ruby, Synthetic Alexandrite, Synthetic Quartz (purple, yellow)
Synthetic Sapphire, Synthetic Diamond, Synthetic Spinel
Synthetic Opal
Stones like Lapis Lazuli, Turquoise, Coral and Jade are also artificially produced.

5) What are the misnomers/trade names used by gem traders?
Sometimes traders sell a gem under a misleading name usually to make it seem more valuable. Some such misnomers are given below:

Correct name of the gemstone Misnomer/trade name
Amazonite Korea jade
Aventurine Quartz Indian jade
Chalcedony(dyed) Swiss jade, black onyx
Chrysoberyl Oriental Sapphire
Chrysoprase Australian jade
Garnet California ruby, Cape ruby
Garnet (green) African jade
Iolite Water Sapphire, Lux sapphire
Jasper (dark green) Oregon jade
Jasper (dyed blue) German lapis/ Swiss lapis
Moonstone Ceylon opal
Peridot Evening emerald
Quartz (citrine) Golden topaz
Quartz (rose quartz) Bohemian ruby
Quartz (dyed) Indian emerald
Spinel Spinel ruby, Spinel sapphire, Balas ruby
Topaz Brazilian ruby
Tourmaline (green) Brazilian emerald
Zircon Ceylon diamond

6) What are the common synthetic gemstones encountered in the Mineralogy and Gem Testing Lab of the department?
Synthetic ruby , Synthetic sapphire,   Synthetic spinel,  Synthetic cubic zirconia and   Synthetic Yellow Sapphire
Synthetic ruby            Synthetic sapphire              Synthetic spinel

Synthetic cubic zirconia                   Synthetic Yellow Sapphire

7) What is Nagamanikya?
Nagamanikya (stone obtained from or guarded by snake) is a myth; found only in Indian mythology. The existence of such a stone is just a story spread around by fraudulent people. No standard gemmology text books refer to such a stone.

8) What are the common gemstones found in Kerala?
Kerala does not occupy a prominent place in the gemstone deposit map of India. Meagre deposits of good quality chrysoberyl cat's eye and alexandrite occur in the southern districts of the state. Sporadic occurrences of ruby, sapphire, topaz and aquamarine have been reported.