First of all, 'Moh's Hardness Scale' is not a physical scale. It is not a physical device or a weighing machine used to weigh the weight (carat) of the stones.

The Moh's hardness scale for minerals has been used since 1822. It simply consists of 10 minerals arranged in order from 1 to 10. Diamond is rated as the hardest and is indexed as 10; talc as the softest with index number 1.The steps are not of equal value and the difference in hardness between 9 and 10 is much greater than between 1 and 2.

Hardness is the property of a material that enables it to resist plastic deformation, usually by penetration. However, the term hardness may also refer to resistance to bending, scratching, abrasion or cutting.

The hardness is determined by finding which of the standard minerals the test material will scratch or not scratch; the hardness will lie between two points on the scale - the first point being the mineral which is scratched and the next point being the mineral which is not scratched. Some examples of the hardness of common metals in the Moh's scale are copper between 2 and 3 and tool steel between 7 and 8. This is a simple test, but is not exactly quantitative and the standards are purely arbitrary numbers.

There are lot of tests available to check the hardness of a gem mineral. But Moh's hardness scale is the widely known one. It is the only acceptable scale among all the gem dealers around the globe.
If a gem dealer says, for example, 'hardness of Apatite is 5', that means, 'the hardness of Apatite on Moh's hardness scale is 5'.

* This hardness scale is for reference only.
 We are not responsible for any mistakes in this list.

_____________________________________________________

You may refer the following list  which includes almost all the available gemstone's properties.

 

Name Structure Specific Gravity Refractive index Doubly Refracting (bi-refraction) Achroite ( Tourmaline ) Trigonal 3.06 1.62 - 1.64 0.018 Agate ( Chalcedony) Trigonal 2.61 1.53 - 1.54 0.004 Albite Triclinic 2.64 1.54 - 1.55 0.009 Almandine ( Garnet ) Cubic 4.00 1.76 - 1.83 None Amber Amorphous 1.08 1.54 - 1.55 Not Available Amblygonite Triclinic 3.02 1.57 - 1.60 0.026 Amethyst ( Quartz) Trigonal 2.65 1.54 - 1.55 0.009 Andalusite Orthorhombic 3.16 1.63 - 1.64 0.010 Andradite Garnet   Cubic 3.85 1.85 - 1.89 None Anglesite  Orthorhombic 6.35  1.87 - 1.89   0.017 Apatite  Hexagonal  3.20  1.63- 1.64   0.003  Aquamerine ( Beryl ) Hexagonal 2.69 1.57 - 1.58 0.006 Aragonite Orthorhombic 2.94 1.53 - 1.68 0.155 Aventurine ( Quartz ) Trigonal 2.65 1.54 - 1.55 0.009 Axinite Triclinic 3.28 1.67 - 1.70 0.011 Azurite Monoclinic 3.77 1.73 - 1.84 0.110 Barite Orthorhombic 4.45 1.63 - 1.65 0.012 Benitoite Hexagonal 3.67 1.76 - 1.80 0.047 Beryllonite Monoclinic 2.83 1.55 - 1.56 0.009 Bloodstone ( Chalcedony ) Trigonal 2.61 1.53 - 1.54 0.004 Braziliznite Monoclinic 2.99 1.60 - 1.62 0.021 Brown Quartz Trigonal 2.65 1.54 - 1.55 0.009 Calcite Trigonal 2.71 1.48 - 1.66 0.172 Carnelian ( Chalcedony ) Trigonal 2.61 1.53 - 1.54 0.004 Cassiterite Tetragonal 6.95 2.00 - 2.10 0.100 Celestine Orthorhombic 3.98 1.62 - 1.63 0.010 Cerussite Orthorhombic 6.51 1.80 - 2.08 0.274 Chalcedony Trigonal 2.61 1.53 - 1.54 0.004 Chatoyant Quartz Trigonal 2.65 1.54 - 1.55 0.009 Chrysoberyl Orthorhombic 3.71 1.74 - 1.75 0.009 Chrysocolla Monoclinic 2.20 1.57 - 1.63 0.030 Chrysoprase (Chalcedony) Trigonal 2.61 1.53 - 1.54 0.004 Citrine ( Quartz ) Trigonal 2.65 1.54 - 1.55 0.009 Coral Trigonal 2.68 1.49 - 1.66 Not Available Danburite Orthorhombic 3.00 1.63 - 1.64 0.006 Datolite Monoclinic 2.95 1.62 - 1.65 0.044 Diamond Cubic 3.52 2.42 None Diopside Monoclinic 3.29 1.66 - 1.72 0.029 Dioptase Trigonal 3.31 1.67 - 1.72 0.053 Dolomite Trigonal 2.85 1.50 - 1.68 0.179 Dravite ( Tourmaline) Trigonal 3.06 1.61 - 1.63 0.018 Dumortierite Orthorhombic 3.28 1.69 - 1.72 0.037 Emerald ( Beryl ) Hexagonal 2.71 1.57 - 1.58 0.006 Enstatite Orthorhombic 3.27 1.66 - 1.67 0.010 Epidote Monoclinic 3.40 1.74 - 1.78 0.035 Euclase Monoclinic 3.10 1.65 - 1.67 0.019 Fire Agate (Chalcedony) Trigonal 2.61 1.53 - 1.54 0.004 Fluorite Cubic 3.18 1.43 None Gold Cubic 19.30 None None Goshenite (Beryl) Hexagonal 2.80 1.58 - 1.59 0.008 Grossular (Garnet) Cubic 3.49 1.69 - 1.73 none Gypsum Monoclinic 2.32 1.52 - 1.53 0.010 Hambergite Orthorhombic 2.35 1.55 - 1.63 0.072 Hauyne Cubic 2.40 1.50 none Heliodor ( Beryl ) Hexagonal 2.80 1.57 - 1.58 0.005 Hematite Trigonal 5.20 2.94 - 3.22 0.280 Hessonite (grosular garnet) Cubic 3.65 1.73 - 1.75 none Howlite Monoclinic 2.58 1.58 - 1.59 0.022 Hypersthene Orthorhombic 3.35 1.65 - 1.67 0.010 Indicolite ( tourmaline) Trigonal 3.06 1.62 - 1.64 0.018 Iolite Orthorhombic 2.63 1.53 - 1.55 0.010 Ivory Amorphous 1.90 1.53 - 1.54 not available Jadeite Monoclinic 3.33 1.66 - 1.68 0.012 Jasper (Chalcedony) Trigonal 2.61 1.53 - 1.54 0.004 Jet Amorphous 1.33 1.64 - 1.68 not availble Kornerupine Orthorhombic 3.32 1.66 - 1.68 0.013 Kyanite Triclinic 3.68 1.71 - 1.73 0.017 Labradorite Triclinic 2.70 1.56 - 1.57 0.010 Lapis Lazuli ( Lazurite) various 2.80 1.5 none Lazulite Monoclinic 3.10 1.61 - 1.64 0.031 Malachite Monoclinic 3.80 1.85 0.025 Meerschaum Monoclinic 1.50 1.51 - 1.53 none Microcline Triclinic 2.56 1.52 - 1.53 0.008 Milky Quartz Trigonal 2.65 1.54 - 1.55 0.009 Moonstone Monoclinic 2.57 1.52 - 1.53 0.005 Morganite ( beryl) Hexagonal 2.80 1.58 - 1.59 0.008 Nephrite ( jade) Monoclinic 2.96 1.61 - 1.63 0.027 Obsidian Amorphous 2.35 1.48 - 1.51 none Oligoclase Triclinic 2.64 1.54 - 1.55 0.007 Onyx Trigonal 2.61 1.53 - 1.54 0.004 Opal Amorphous 2.10 1.37 - 1.47 none Orthoclase Monoclinic 2.56 1.51 - 1.54 0.005 Padparasha ( Corundum) Trigonal 4.00 1.76 - 1.77 0.008 Pearl Orthorhombic 2.71 1.53 - 1.68 not availble Peridot Orthorhombic 3.34 1.64 - 1.69 0.036 Petalite Monoclinic 2.42 1.50 - 1.51 0.014 Phenakite Trigonal 2.96 1.65 - 1.67 0.015 Phoshophyllite Monoclinic 3.10 1.59 - 1.62 0.021 Plasma ( Chalcedony) Trigonal 2.61 1.53 - 1.54 0.004