HARDNESS

HARDNESS

• HARDNESS is not related to toughness
• HARDNESS test is potentially destructive
• HARDNESS test is conducted on rough crystals
• AT THE BACK OF OPAQUE CABOCHON AND CARVED PIECES    
  
                  

CHEMICAL COMPOSITION

CHEMICAL COMPOSITION

1. Carbon and Silicates are chemically resistant
2. Silicates are more durable
3. Carbonates are less Durable and can react easily e.g PEARL , CORAL , and SHELLS.
   
   
   
   

DURABILITY DEPENDS UPON

DURABILITY DEPENDS UPON

1. ATOMIC STRUCTURE
2. CHEMICAL STRUCTURE 

• SHORT BANDS are  Strong e.g in Diamond
• LONG  BANDS are weak as in Graphite

DURABILITY OF GEMS MATERIALS

DURABILITY OF GEMS MATERIALS

• DURABILITY  is combination of three parameters.

1. HARDNESS:     Resistance to Scratching
2. TOUGHNESS:   Resistance to Breaking
3. STABILITY :  Resistance to Chemicals, Heat , Humidity and light

•                  GEMS STONE DURABILITY

1. Jade Is The Toughnest Stone
2. Gems Which Are Found In Sand And Gravel Are Durable.
3. Because They Have Been Exposed To Weathering And Abrasion During Transporation
4. Such Stones Are Mostly Rounded e.g QUARTZ , TOPAZ, CORUNDUM, SPINAL, CHRYSOBERYL, DIAMOND and GARNET

Minerals Defination

Minerals are substances that are formed naturally in the Earth. Minerals are usually solid, inorganic, have a crystal structure, and form naturally by geological processes. The study of minerals is called mineralogy. A mineral can be made of single chemical element or more usually a compound.