A Smarter Way to Understand Diamond Size, Value & Beauty
When shopping for a diamond, carat weight is often one of the first details buyers focus on — and for good reason. But here’s the truth: carat doesn’t mean size. It refers to weight, not how large a diamond looks on the finger.
At Tang&Co, we believe that understanding diamond carat weight can help you get a more impressive-looking diamond without overspending. Let’s break it all down — from size and price to myths, shape factors, and smart shopping tips.
What Is a Carat?
A carat is a unit of weight used specifically for measuring gemstones, including diamonds.
1 carat = 0.2 grams (or 100 “points”).
So a 0.50ct diamond may be referred to as a “50-pointer,” while a 1.00ct stone is a full carat.
Despite the common misconception, carat weight doesn’t directly equal physical size — two diamonds with the same carat weight can appear very different in size, depending on their cut, depth, and shape.
Carat Weight vs. Diamond Size
While carat measures weight, diamond size refers to its actual physical dimensions (like diameter).
For example:
A 1.00ct round diamond typically measures around 6.4–6.5mm in diameter.
A 1.50ct stone? About 7.3mm.
That’s just a 0.8mm increase, yet it can double the price.
Also, diamond shape plays a major role:
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Oval, marquise, and pear shapes tend to appear larger per carat.
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Asscher and princess cuts often face up smaller due to deeper cuts.
Do Other Gemstones Weigh the Same?
No — gemstone density varies.
For instance, rubies and sapphires are denser than diamonds, meaning a 1ct ruby looks smaller than a 1ct diamond.
Likewise, topaz may appear even smaller.
This is why carat comparisons across gemstone types are rarely apples-to-apples.
Why Carat Weight Impacts Price
As diamonds get larger, they become exponentially rarer.
That’s why a 1ct diamond may cost 3–5x more than a 0.50ct stone of similar quality.
There are also "magic sizes" — 0.50ct, 0.75ct, 1.00ct — that are especially sought after, which drives up price.
✨ Tang&Co. Tip:
To save without sacrificing beauty, consider diamonds just below these thresholds:
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0.92ct instead of 1.00ct
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0.47ct instead of 0.50ct
Visually, the difference is minimal — but the price savings can be significant.
A Brief History of the Carat
The term carat comes from the carob seed, once used as a unit of measurement for gemstones because of its (supposedly) uniform weight.
In 1907, the carat was standardized as 0.2 grams across the global jewelry industry — creating the system we use today.
Final Thoughts: Carat Weight Isn’t Everything
While carat weight affects price and presence, it’s just one part of the picture.
To get a diamond that truly stands out, focus on cut quality and stone shape — these factors impact brilliance, size appearance, and value far more than carat weight alone.
At Tang&Co, we’re here to help you make a confident, well-informed decision — so you get the perfect diamond, with perfect presence, at the right price.