4 mm Round Lab-Grown Diamond, Loose

A 4 mm round lab-grown diamond, D to F color, VVS clarity, sold individually. This is the threshold where a stone moves from accent role to a stone you can clearly see when worn.

What the 4 mm threshold means

Below 4 mm, the person facing you sees the row of stones, not each stone. From 4 mm up, each stone starts to have its own shape at normal conversation distance.

That's why this size is often chosen for small everyday studs, delicate single-stone pendants, or a plain ring set with a single stone. Those pieces don't need a large stone, just one neat point of light.

When to choose 4 mm over 4.5 mm

Half a millimetre apart, but the price gap is significant, because stone prices rise faster than size. If you're making studs for daily work wear or a pendant worn constantly, 4 mm is lighter and more discreet, and leaves budget for a sturdier setting.

If, on the other hand, the piece is for special occasions and you want the stone to stand out, go up to 4.5 mm or more. At sizes this small, saving half a millimetre is usually a false economy.

Setting

Four prongs show the most of the stone, so it looks a little larger; six prongs hold more securely for constant wear. For studs, our setters usually recommend four prongs because ears take fewer knocks than hands.

If you're replacing a stone on an older piece, bring the piece in so our setter can measure the seat. A seat that's two or three tenths of a millimetre off won't hold the stone securely, and that error is very hard to catch at home.

Keeping the stone bright

A stone this size usually sits on a piece worn every day, so it picks up oil quickly. Wipe with a soft cloth after each wear, and wash thoroughly with warm water and a soft brush once a week.

Oil trapped under the stone is the most common reason a diamond loses its fire — not scratches. Clean it properly and it sparkles like new.