When it comes to fine jewellery, every detail matters. As a customer, you often spend time carefully choosing the perfect gemstone, considering the colour, cut, clarity, and of course, the size. So when a stone arrives and doesn’t measure exactly what was listed — for example, a 6mm gem that measures 5.9mm — it’s natural to wonder “Is this the right size?”.
The truth is, in the world of natural gemstones, small size variations are completely standard — and often unavoidable. That’s because gemstones aren’t mass-produced, they’re shaped from natural materials, cut by hand and crafted to enhance their beauty rather than fit into an exact mould.
So whether you’re browsing engagement rings, designing a bespoke piece, or simply curious — here’s everything you need to know about gemstone sizing.
What Is A Size Tolerance?
In the jewellery industry, size tolerance refers to the small, industry-accepted range of variation in a gemstone’s size. The standard tolerance is ±0.2mm, meaning that a gemstone described as 6mm could actually measure anywhere from 5.8mm to 6.2mm — and still be considered accurately sized.
Why Don’t Gemstones Measure Exactly The Same?
There are a few key reasons — firstly, no two natural gemstones are identical. They’re formed deep within the earth over millions of years, and every stone carries unique properties — from colour and clarity to size and structure.
Additionally, unlike machine-made items, gemstones are cut by hand. Even with highly skilled cutters and precision tools, tiny variations are inevitable. It’s part of what makes your stone unique.
It is also important to remember that gemstones of different shapes appear differently, even when they are the same size. For instance, a 6x4mm oval will not look the same as a 6mm round diamond, as the surface area is different.
What This Means For You
If you’re buying or designing a piece with a specific stone size in mind, here’s what you need to know:
- Slight size variation is completely normal.
- A 6mm gemstone may actually measure anywhere between 5.8mm and 6.2mm.
- This does not affect the beauty, quality, or value of your stone.
- All our gemstones are cut and measured within industry-standard tolerances.
Our Commitment To Transparency
At
Diamonds Factory, we believe in complete transparency. Our goal is to help you feel confident and informed at every step of your jewellery journey — and to love your piece not just when it arrives, but for years to come. We understand that buying fine jewellery is a personal experience, so we're here to help guide you through it. If you have questions about gemstone sizing, carat weights, or how your particular stone will appear in a design, our team is always happy to assist.
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When it comes to fine jewellery, every detail matters. As a customer, you often spend time carefully choosing the perfect gemstone, considering the colour, cut, clarity, and of course, the size. So when a stone arrives and doesn’t measure exactly what was listed — for example, a 6mm gem that measures 5.9mm — it’s natural to wonder “Is this the right size?”.
The truth is, in the world of natural gemstones, small size variations are completely standard — and often unavoidable. That’s because gemstones aren’t mass-produced, they’re shaped from natural materials, cut by hand and crafted to enhance their beauty rather than fit into an exact mould. So whether you’re browsing engagement rings, designing a bespoke piece, or simply curious — here’s everything you need to know about gemstone sizing.
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What Is A Size Tolerance?
Why Don’t Gemstones Measure Exactly The Same?
What This Means For You
- Slight size variation is completely normal.
- A 6mm gemstone may actually measure anywhere between 5.8mm and 6.2mm.
- This does not affect the beauty, quality, or value of your stone.
- All our gemstones are cut and measured within industry-standard tolerances.
Our Commitment To Transparency