Knowing where a stone falls on this scale isn’t just trivia; no, it’s very valuable information. It can make the difference between a piece that lasts for generations and one that comes back cracked or dulled. We all have experienced this pain at some point in our careers as makers.
🤔 What Is Mohs Hardness & Why Does It Matter?
The Mohs scale of hardness ranks gemstones from 1 (softest) to 10 (hardest), based on their resistance to scratching. Diamonds sit at the very top with a perfect 10, while talc sits at the bottom with a 1.
But there is a catch: hardness doesn’t mean unbreakable. A diamond may be the hardest stone, but it still has cleavage planes that make it prone to chipping if struck. That’s why understanding hardness is about more than numbers; it’s about knowing how a stone will behave in real life, and respecting that.
For jewellers, Mohs hardness tells you:
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Which stones can handle daily wear (sapphires, spinel, ruby, diamonds).
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Which need protective settings (pearls, opals, turquoise, preferably emeralds and tanzanite too).
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Which stones are at risk in ultrasonic cleaners or plating baths, I’ve included plating, as this is often overlooked and actually can destroy a piece at the very end of a job, so huge disappointment and cost can be avoided with this information, I can speak from my own experience on this as a maker so it’s worth sharing.
✨ Gemstone Care Guide: Safe, Caution & Not Safe
Not all stones can be treated the same way in the workshop. Our Gemstone Care & Risk Master Guide groups gems into three easy-to-remember categories:
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✅ Safe Stones- durable, stable, and generally fine in ultrasonic cleaners or plating baths (with a few caveats like avoiding fracture-filled or coated stones). If in doubt at all then don’t risk it. Washing with a soft brush and some fairy or other washing up liquid will break the grease and dirt down or you can use a steam cleaner.
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⚠️ Caution Stones - often stable, but risky if they have inclusions, cleavage, or certain treatments. Handle carefully and double-check before cleaning or plating.
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❌ Not Safe Stones - porous, brittle, or organic stones that should never go near ultrasonic cleaners or plating solutions. EVER!!
This simple framework helps reduce mistakes in the workshop and builds confidence in how you handle customer pieces.
👉 Download the full poster guide here
👍 Why This Knowledge Is a Game-Changer for Jewellery Stores AND makers
If you run a shop or workshop, gemstone knowledge isn’t just for the bench jewellers; it’s for your whole team. Imagine your staff confidently explaining to a customer, and then how proud you will be of the team member.
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Why their opal engagement ring needs gentle cleaning.
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Why plating a turquoise pendant is risky. And it’s a no…
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Why a diamond ring with fracture-filling should never go in the ultrasonic.
Moments like these build trust. Customers see you not only as a seller, but as an expert and caretaker of their jewellery. And inside the workshop, this knowledge reduces costly mistakes, fewer cracked stones, fewer awkward conversations, and a smoother repair process. All this adds up to a professional business practice .
🧐 Final Thoughts
The Mohs scale may be over 200 years old, but it remains one of the most useful tools in jewellery making. Paired with a modern care guide, it gives jewellers, students, and store staff the confidence to handle gemstones safely.
So next time you’re at the bench or on the shop floor, remember: a little gemstone knowledge doesn’t just protect the stones - it makes you look good, too.
👉 Don’t forget to grab your copy of the Gemstone Care & Risk Master Guide to keep by your side.