Loose Diamonds  

An engagement diamond may be the biggest purchase you've ever made. And with the right information, you'll be able to spend your budget on the diamond qualities that are most important to you. Read on and we'll provide you with a thorough understanding of diamond quality.

Choose Your Diamond Shape

To start, find out what shape she likes. Popular diamond shapes include round, oval, princess-cut, emerald-cut, Asscher-cut, marquise-cut, radiant-cut, pear-shaped, and heart-shaped diamonds. The majority of diamond engagement rings today are set with a round diamond. And most of the remaining rings are set with princess-cut diamonds.

Diamond Shapes

Choose Your Diamond Size

See the chart below to get an idea of the size of diamond that best suits your budget. You'll find a wide range of diamond sizes is available within a given budget. Next, you'll narrow this range when you decide on the quality of your diamond.

Diamond Size
Starting at £613.00 Starting at £1,327.00 Starting at £1,787.00 Starting at £3,726.00 Starting at £4,951.00
Price comparison: D–J colour, FL–SI2 clarity, Ideal–Fair cut. Prices and measurements are approximate.

Choose the Four Cs of Diamond Quality

At Blue Nile, it's our goal to help all our customers make an educated, confident buying decision. Below is a summary of what you'll find in our Diamond Education.


The cut of a diamond has the biggest effect on its sparkle, also called brilliance. Even with perfect colour and clarity, a poor cut can make a diamond look dull. We carry only Ideal, Very Good, Good, and Fair cut diamonds, which produce the most brilliance.


Colourless diamonds are most highly valued and are priced accordingly. For the best value, choose a colourless or near-colourless diamond that has no noticeable colour, grades D-J. These are the only grades of diamond colour offered by Blue Nile.


Diamonds free from internal flaws, or inclusions, are very rare and highly-valued. The best value in diamond clarity is a diamond with no inclusions visible to the unaided eye. Blue Nile only offers diamonds graded FL–SI2, some of the clearest diamonds available.

Carat weight:

Since larger diamonds are more rare than smaller diamonds, diamond value rises exponentially with carat weight. With a clear understanding of cut, colour, and clarity, you can balance the overall diamond quality with the size of your diamond.