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precious stones
all about stones, gemstones and precious stones....

moh hardness scale

Each gem and / or mineral has it's own classifications. One scale of defining the characteristics of minerals is Mohs Scale of hardness: (10 is the hardest)

 

10 Diamond
 9Corundum
 8Topaz
 7Quartz
 6Orthoclase 
 5Apatite
 4Fluorite
 3Calcite
 2Gypsum
 1Talc 

 

 

some stone hardnesses

 10

Diamond 

 9

Ruby, Sapphire

 8

Topaz, (Beryl 7.5)

 7

Quartz, (Garnet 6.5 - 7.5)

 6

Tanzanite (Opal 5.5 - 6.5)

 5

Lapis Lazuli 5.5

 4

Pearl 2.5 - 4.5

 3

Coral 3 - 4

 2

Amber

 

Dana mineral classification

The old Dana classification system of metals, minerals and oxides: ( not to be confused with mohs scale of hardness, the numbers on the right are classifications of minerals, the updated modern Dana Classification counts over 78 different classifications)

 

 1

Native elements: such as metals, semi-metals and non metals (1)

 2

Sulphides and Sulphosalts: Sulphur and metals ores (2 - 3)

 3

Oxides and Hydroxides: Metal and Oxygen ie: corundum (4 - 8)

 4

 Halides: Metal and Halogen elements: ie: flourite (9 - 12)

 5

Carbonates, Nitrates and Borates: Carbon and oxygen group (13 - 27)

 6

Sulphates, Chromates and Molybates: Sulphur and oxygen group (28 - 36)

 7

Phosphates, Arsenates and Vandates: metal and phosphates (37 - 49)

 8

Organic: minerals formed from living organisims: ie amber and pearls (50) 

 9

Silicates: Silicon and Oxygen group almost a third of all minerals (51 - 78)

 

zodiac stone chart

The Zodiac stone chart

 

January 20 - February 18 = Aquarius = Garnet

February 19 - March 20 = Pisces = Turquoise

March 21 - April 20 = Aries = Diamond

April 21 - May 20 = Taurus = Tourmaline

May 21 - Jun 20 = Gemini = Aquamarine

Jun 21 - July 20 = Cancer = Ruby

Jul 21 - Aug 21 = Leo = Clear Quartz

Aug 22 - Sept 22 = Virgo = Sapphire

Sept 23- Oct 22 =Libra = Peridot

Oct 23 - Nov 21 = Scorpio = Topaz

Nov 22 - Dec 21 = Sagittarius = Amethyst

Dec 21 - Jan 19 = Capricorn = Onyx

 

birth stone chart

Birth Stone Chart

 

  • January = Garnet

  • February = Amethyst

  • March = Aquamarine

  • April = Diamond

  • May = Emerald

  • June = Pearl (and Moonstone, Alexandrite )

  • July = Ruby

  • August = Peridot

  • September = Sapphire

  • October = Opal  ( and Tourmaline )

  • November = Topaz ( and  Citrine )

  • December = Turquoise ( and Zircon, Tanzanite )

  •  

    Clarity

    The Clarity of a stone relates to the presence of any features within the stone. In the jewellery trade, the presence of any structure variances or other sediments within a precious stone would be called impurites and structural flaws.

    Sometimes there are small dots within the diamond which appear black when light passes through the stone. These features are known as inclusions and appear in various sizes and number as small spots, cloudy groupings, scratches, and often resemble cracks or cleavages. Cracks and cleavages can be caused by other external or internal influences and are also know as flaws.

    The entire structure of a stone through it's formation can ultimately influence the state it is found in when mined / collected. Most stones can warp and twist away from the common state and shape it is found in. Crystals are well known for many different patterns of growth, as is organic materials.

    The presence of any other sediment, oxides and heat during the stones structure can affect the stone's  clarity and characteristics. Often a stone is fused with other materials such as crystals or other intrusions. The presence of such elements can also affect aspects such as the colour, and can even morph two stones together. External features such as polish, chips, scratches, surface blemishes and damage influence the clarity.

    The clarity of a diamond / precious stone would ultimately affect it's brilliance and colour. Heavily flawed or included stones will be less durable and appear darker. The overall size of a stone would influence how strictly the clarity is graded.

    IF - flawless
    IF 
    vvs1
    VVS1 
    vvs2
    VVS2
    vs1
    VS1 
    vs2
    VS2
    SI1
    SI1 
    SI2
    SI2 
    1stPK
    P1
    2ndPK
    P2
    P3
    P3 

      
    IF - Flawless  

     Internally Flawless to Flawless stones have no visible flaws or inclusions with 10 x magnification , also called Loupe Clean

     
     VVS - VVS1 - VVS2

     Very Very Small Inclusions that are difficult to see with 10 x magnification

     
     VS - VS1 - VS2

     Very Small Inclusions that are moderate to easily found with 10 x magnification

     
     SI - SI1 - SI2

    Small Inclusions that are easily seen under magnification. Difficult to see or slightly noticible to the eye alone

     
     P - P1 - P2 - P3 Pique inclusions easily found under 10 x magnification and with the eye alone

     


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