The Moh's 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 Moh's 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 Moh's scale?" and "what materials besides diamonds are good for everyday-wear fine jewelry?"
MOH'S SCALE: WHAT IS IT!?
First, where did this Moh's 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 Moh’s 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.
WHAT'S THE SCALE?
Here is a list of some common materials, minerals, gemstones and other objects...with how each ranks on the modern Moh's scale:
9.5: Diamond-coated drill pieces and diamond-coated files
9.0: Corundum, Emery Cloth, Emery Boards (fingernail file), Ruby, 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: 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 cubic zirconia jewelry! Our 5A/AAAAA CubicZirconia.com Cubic Zirconia ranks at an 8.5 hardness on the Moh’s scale and only objects that have the same or higher number can scratch it.
Please note that “cubic zirconia” is sold now by other companies than the official CubicZirconia.com-- and we are not responsible for their stones’ quality, hardness or suitability for precious metal jewelry such as what we create and sell. Inferior cubic zirconia may not be as hard and durable as it should be and what Wikipedia says the substance is since methods of making the stones vary and not every maker has the same standards, quality control, or integrity.
WHAT'S THIS MEAN FOR ME?
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 Moh's scale will be scratched. Yes, that means any jewelry made of those materials with Moh's 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 Moh's scale rank of greater than or equal to 7.0.
As noted, our 5A (AAAAA) cubic zirconia stones rate an 8.5 on the Moh's scale of mineral hardness. For your information, that is just below ruby (9.0) or sapphire (9.0), and are harder than aquamarine, morganite and emerald (each 7.5-8); harder than amethyst, citrine, garnet, quartz, and tourmaline (each 7-7.5); and harder than peridot, tanzanite, opal or jade (each 5.5-7). Indeed, our 5A diamond-quality cubic zirconia 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 cubic zirconia 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 Cubic Zirconia: only an object harder than a cubic zirconia can scratch a CZ (and there aren’t many of these), but it can also scratch itself if two pieces of cubic zirconai jewelry are jumbled together in a jewelry box.
One of the reasons we tried to make this article about the Moh's 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, cubic zirconia, 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 CZ jewelry in your jewelry box, AT MINIMUM you separate each cubic zirconia piece of jewelry from these kinds of jewelry: Diamond, Cubic Zirconia, Alexandrite, Cat's Eye, Chrysoberyl, Ruby, Sapphire, Tungsten Carbide, and watches.
In a perfect world, it wouldn't be just your cubic zirconia 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.
We discuss more specifics on safe fine jewelry storage here in this blog post “How to store your fine cubic zirconia jewelry safely”...including how specifically to store and keep rings, necklaces, pendants and earrings.