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The Moh's Scale of Hardness and How to Protect your Jewelry from Unwanted Scratches

The Moh's Scale of Hardness and How to Protect your Jewelry from Unwanted Scratches

The Mohs' Scale of Hardness ranks minerals, gemstones, metals and other materials based on what material scratches what other materials, and what materials are scratched by it in return. Basically, a material can be scratched by anything ranked above it and can scratch anything ranked below it. This is important because you're going to learn how to mostly prevent the #1 reason fine precious metal jewelry becomes damaged and doesn't last the lifetime you expect it to last!

The scale goes from one (1.0) to ten (10.0). At the lower end of the spectrum, materials are fragile and easily scratched. For example, talc (the soft material in baby powder) has a rank of 1.0. At the higher end of the spectrum, materials are the most-durable and hardest-to-scratch. A diamond has a rank of 10.0. Diamond isn't the only material that does fine for long-lasting jewelry, though. See below for what other options are available for fine jewelry to be worn every day! 

In the following blog post, we talk a bit more in-depth about the Mohs' scale and cover other related topics such as "how should I store my jewelry to prevent scratches?", "how does platinum/palladium/gold/silver rank on the Mohs' scale?" and "what materials besides diamonds are good for everyday-wear fine jewelry?"


First, where did this Mohs' scale come from, anyway? A Viennese mineralogist named Fredrich Mohs (1773-1839) created the scratch hardness test to measure the resistance-- or relative hardness-- of a mineral or gemstone when scratched with varying other minerals/gemstones. His work was initially limited just to gemstones and naturally-occurring minerals. The modern Mohs' Scale of Hardness today ranks not just minerals and gemstones, but other materials, metals and objects too (both natural and man-made).

A material’s rank on the scale is based on two things:

1. The ability of one material to scratch any other material with a smaller number on the scale.

2. The fact that a material can be scratched by any material with a higher rank on the scale.


Here is a list of some common materials, minerals, gemstones and other objects...with how each ranks on the modern Mohs' scale:

10.0: Diamond 
9.5: Diamond-coated drill pieces and diamond-coated files
9.25: Moissanite
9.0: Corundum, Emery Cloth, Emery Boards (fingernail file), Ruby, Sapphire, White Sapphire, Scratch-proof glass (watches), Tungsten Carbide
8.5: Alexandrite, Cat's Eye, Chrysoberyl 
8.0-8.5: Cubic Zirconia
8.0: Sandpaper, Spinel, Topaz 
7.5-8.0: Aquamarine, Beryl, Emerald, Morganite, Red Beryl 
7.5: Hardened Steel, Tungsten
7.0-7.5: Tourmaline, Zircon 
7.0: Amethyst, Bloodstone, Carnelian, Chalcedony, Citrine, Onyx, Peridot, Quartz 
6.5-7.5: Garnet, Peridot, Rhodolite, Tsavorite 
6.5: Stainless Steel, Tanzanite
6.0-6.5: Labradorite, Moonstone 
6.0: Feldspar, Jade, Rhodium, Titanium
5.5-6.5: Opal
5.5: 950 Palladium, Cobalt, Hematite  
5.0: Apatite, Obsidian, Pure Palladium, Steel, Tooth enamel, Turquoise
4.50 950 Platinum, Iron, Variscite
4.0: Fluorite, Nickel 
3.50-4.50: Toothpaste (most brands)
3.5: 14K Yellow Gold, Pure Platinum
3.0: Brass, Bronze, Calcite, Copper
2.75: 18K Yellow Gold
2.5: 24k Pure Gold, Aluminum, Silver, Zinc 
2.0: Gypsum, Rock Salt
1.5: Graphite, Lead, Tin
1.0: Talc (e.g. baby powder)

For your easy reference, we have bolded and underlined the materials from which we ourselves make fine white sapphire jewelry!

Our genuine WhiteSapphire.com white sapphires rank at an 9.0 hardness on the Mohs' scale and only objects that have the same or higher number can scratch it.


The most important number on this scale is 7.0.

Why? It's because 7.0 is the hardness of quartz, which is the hardest mineral that is commonly found floating around in the air as part of what we would normally call "dust".

If the dust contains minute particles of quartz, then any mineral that is below quartz (7.0) on the Mohs' scale will be scratched. Yes, that means any jewelry made of those materials with Mohs' rank < 7.0 will be scratched over time just from "dust"!

It is for this and other reasons that fine jewelers typically recommend jewelry to be worn every day should be made of materials with no less than a Mohs' scale rank of greater than or equal to 7.0. 

As noted, our genuine white sapphire stones rate an 9.0 on the Mohs' scale of mineral hardness. For your information, that is just below diamond (10.0) and moissanite (9.5). Indeed, our genuine white sapphire stones are harder than most other colored birthstones! Cool, huh? (Wikipedia: Source).

All those listed with ranks 7.0 and above are great options for daily-wear jewelry. While we love and some of our team personally wear jewelry made of peridot, tanzanite, opal and jade...it's tough to recommend jewelry made from these materials for "daily" wear jewelry like an engagement ring.


Diamond (10.0) scratches everything below it, and that’s why you shouldn’t store diamonds in the same jewelry box where they can touch other genuine or imitation stone jewelry (it’ll scratch jewelry made with every other common material, including white sapphires and all real and artificial gemstones, not to mention gold, silver, or platinum). 

You read that right! It’s not safe to store diamonds alongside anything else, as it will scratch everything else you have in your jewelry box when they touch. 

Did you know that even though diamonds are the hardest minerals, they can still be scratched?

What could possibly scratch a diamond?

Another diamond!

The same goes for white sapphires: only an object harder than a white sapphire can scratch it (and there aren’t many of these), but it can also scratch itself if two pieces of white sapphire jewelry are jumbled together in a jewelry box. 

One of the reasons we tried to make this article about the Mohs' scale of hardness interesting is to take a boring topic and give you a reason to read it. We hope the result helps our customers to prevent scratches to your jewelry - whether it be diamond, white sapphire, emerald, ruby, gold, silver, palladium, platinum or other-- by being aware of the other objects that you/your jewelry may come into contact with in a given day and over a lifetime of wear and storage

We recommend that when you put your white sapphire jewelry in your jewelry box, AT MINIMUM you separate each white sapphire piece of jewelry from these kinds of jewelry: diamonds, moissanites, other white sapphires.

In a perfect world, it wouldn't be just your white sapphire jewelry you protect! You just wouldn't jumble your jewelry pieces made of ANYTHING in a drawer or jewelry case where they can easily scratch one another. 

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  • whitesapphire Admin