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Diamond Carat Size Guide: How Big Should Your Diamond Be?

Diamond carat is the weight (not strictly “size”), and perception of size depends on cut, setting and finger proportions. This diamond size guide explains carat, price implications and how to visualise different carat weights on the hand.

Carat = weight, mm = diameter

A carat is 200 mg. For example, a well-cut 1.00 ct round diamond typically measures around 6.5 mm in diameter; smaller or larger diameters at the same weight depend on cut proportions. Use a size chart to compare real-world appearances.

As a practical rule, a narrower finger makes the same diamond appear larger; conversely a wider finger reduces perceived spread. If you can, test a diamond on the finger rather than relying on photos — mm measurements are helpful, but the live view is decisive.

Price vs perceived size trade-offs

  • A small change in carat (e.g., 0.9 → 1.0 ct) can cause a disproportionate jump in price.

  • A better cut and setting often increase perceived size more than a marginal carat increase.

Consider halo or pavé settings to boost perceived size, or choose a shape with a larger spread (oval, marquise) for more visual presence at the same carat weight.

Visual guide & in-store test

 

Try 0.50, 1.00 and 2.00 ct stones on your finger — the same carat can look different by shape and cut. We’ll show you the effect of proportions and show how halo or pavé settings increase perceived spread.

 

I recommend a quick checklist for the try-on: note finger coverage, height off the finger, how the wedding band will sit, and how it looks in daylight vs store lighting. That makes comparison straightforward when you leave the showroom.

 

Want side-by-side comparisons? Book a consultation at Olivia Green to see carat sizes, shapes and settings on your hand.

 

See our engagement ring range

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