3 Carat Lab Grown Diamonds: Price, Size and What to Check

Oct 7

2 min read

A 3 carat lab grown diamond measures about 9.4mm across in a round brilliant, and set in solid gold the finished ring runs roughly $2,500 to $3,100. A mined diamond of comparable specification generally starts several times higher.

How big 3 carats actually looks

Carat is weight, not size, so shape changes the footprint considerably:

Round — about 9.4mm
Oval — about 11 × 8mm, and reads largest on the finger
Emerald cut — about 9.5 × 7mm
Cushion — about 8.5mm
Marquise — about 14 × 7mm, the longest of all

Full table in our carat size chart.

What to check at this size

Cut above everything. At 3 carats a poor cut is obvious: the stone looks glassy and dead in daylight. No clarity grade compensates.

Clarity around VS1 to VS2. Inclusions invisible at 1 carat become findable at 3.

Colour G to H. Larger stones hold colour more visibly, so the tint that is undetectable at 1 carat shows at 3.

The bow-tie on oval, marquise and pear shapes. Every elongated stone has one. Judge it face-up in daylight images, never in a studio render.

Certification. IGI is standard for lab grown, and the report number is laser-inscribed on the girdle so you can verify the stone is the one described.

What it costs set in solid gold

Complete rings from our range:

Marquise Cut 3ct Lab Grown Diamond Engagement Ring — $2,723
3ct Pear Cut Lab Grown Diamond Engagement Ring — $2,744
Twisted Band 3ct Round Brilliant Lab Grown Diamond Ring — $2,577
3.5ct Pear Cut Lab Grown Diamond Engagement Ring — $3,025

Prices shown are 18K; 14K is about 12% less and 10K about 22% less.

Is 3 carats too large for everyday wear?

It depends more on setting height and hand size than on the stone. A 3 carat elongated shape set low wears comfortably on most hands. A tall round solitaire at the same weight reads considerably bigger and catches more. If you work with your hands, choose a bezel or a low-profile setting.