Moh's Scale of Hardness for Common Gemstones

Agate = 7

Alexandrite = 8.5

Amber = 2 to 2.5

Amethyst = 7

Apatite = 5

Aquamarine = 7.5 to 8

Aventurine = 7

Bloodstone = 7

Chalcedony = 7

Charoite = 7 (but chips and cracks easily)

Chrysoberyl = 8.5

Citrine = 7

Diopside = 5.5 to 6.5

Fluorite = 4

Garnet = 7 to 7.5

Hematite = 5 to 6.5

Iolite = 7 to 7.5

Jade = 6.5 to 7

Jasper = 7

Kunzite = 6.5 to 7.5

Lapis lazuli = 5 to 6

Malachite = 3.5 to 4.5 

Moonstone = 6 to 6.5

Morganite = 7.5 to 8

Obsidian = 5 to 6

Onyx = 7

Opal = 5.5 to 6.5

Pearl = 2.5 to 4.5

Quartz = 7

Rhodochrosite = 3.5 to 4

Sardonyx = 7

Sodalite = 5.5 to 6

Spinel = 7.5 to 8

Tanzanite = 8.5

Topaz = 8

Tourmaline = 7 to 7.5