4.00 Ct Cushion Blue Sapphire and Lab-Grown Diamond Three Stone Ring

Ring size tells you how the band fits your finger. Diamond size tells you how large the stone looks. Check both before ordering.

Find your fit

The most reliable starting point is to have a jeweler measure the intended finger with ring sizers, ideally in a width similar to your chosen band. A physical ring sizer is also more useful than trying to judge fit from a photograph.

Measure a ring you already wear

1. Choose a round ring that fits the same finger on the same hand comfortably.
2. Measure straight across the widest part of the inside opening, edge to edge, in millimeters. Do not include the metal. A caliper is easier to read precisely than a ruler.
3. Compare that measurement with the inside-diameter column below. Treat a ruler measurement as an estimate; ask us to help if you are between sizes.

US ring size reference

Measurements below are rounded. Check the size selector on your chosen ring for available sizes, including quarter sizes where offered.

Get the fit right

• Measure with your hands at a comfortable temperature, and check more than once. Cold, heat and activity can affect fit.
• The ring should fit comfortably at the base of the finger and pass over the knuckle with some resistance. Large knuckles may need a jeweler's fitting advice.
• Measure the intended hand; do not assume your other hand is the same size.
• Wider bands can feel tighter. Confirm the fit using a similar-width sizer instead of automatically adding a fixed fraction of a size.
• String and paper-strip measurements are rough estimates: tension, stretching and marking errors can change the result. Confirm an uncertain measurement with a physical sizer or jeweler.

See how large the diamond will look

Ask for the center stone's length × width in millimeters, the band width and the setting height. Total carat weight may include side stones, so it does not tell you the center stone's dimensions. A real on-hand photo is most useful when the model's ring size and the stone's measurements are stated.

Buying a surprise?

If possible, borrow a ring worn on the intended finger or ask someone who knows the recipient's size. Do not assume every ring can be resized. Full eternity bands and some settings have restrictions. Contact us about the specific design before choosing a size on that basis; our team can explain resizing options, cost and timing.

Need help? Call (646) 532-9004 or message our NYC team with the product link and any measurements you have.

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