Hardness refers to a material’s resistance to scratching.
Toughness refers to a material’s resistance to breaking or chipping.

A diamond is the hardest known material and is a 10 on the hardness scale. The only material that can scratch a diamond is another diamond.

The Mohs Hardness Scale is shown below and indicates the hardness of various gems and minerals.

Diamond	10
Corundum (Ruby and Sapphire)	9
Topaz	8
Quartz	7
Orthoclase (Feldspar)	6
Apatite	5
Fluorite	4
Calcite	3
Gypsum	2
Talc	1

Additional gemstones and their relative hardness are also show below.

Alexandrite	8.5
Beryl (Emerald, Aquamarine)	7.5 – 8.0
Iolite	7.0 – 7.5
Garnet	6.5 – 7.0
Peridot	6.5 – 7.0
Tanzanite	6.5 – 7.0
Jadeite	6.5 – 7.0
Opal	5.5 – 6.0
Lapis Lazuli	5.0 – 6.0
Turquoise	5.0 – 6.0
Pearl	2.5 – 3.5
Gold	2.5 – 3.0
Amber	2.0 - 2.5

The significance of hardness is important when it comes to wearing your jewelry. Stones that measure 6.5 or higher on the hardness chart are good for everyday wear in a ring. However, even these stones will abrade over time. Stones falling below 7 are a little more sensitive to scratching and are best worn in pendants and earrings when worn on a daily basis. Knowing where your gem falls on the hardness scale is advised so that you know the best way to wear and maintain your jewelry.

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