Quick and Easy Buying Guide

Carat weight: 1 carat = 200 milligrams = 6.5 mm diameter. Doubling weight doesn't double diameter.

Diamond clarity: FL/IF/VVS/VS = super expensive, near perfect. SI = best value if you can check a photo for obvious inclusions (defects).


Color: D-G = colorless, expensive, only if you have money to burn. H-J = best value. Can go lower in gold metal settings than white metal.

Cut: Better cut ratings let more light into a diamond, making it sparkle more. Very important property, don't skimp here.

Set a budget and minimum cut (Premium). Go J color for gold and I/H for white metals. Go searching for SI1/SI2 clarity diamonds at James Allen. Pick a diamond with small/no inclusions. Choose a ring setting and buy it risk-free (60-day returns).

Diamond Carat Weight

This page gives key details and illustrations on the size of diamonds, often referred to as the diamond carat weight or diamond carat size.

If you are looking for pictures that show you how big a diamond of a certain carat weight appears on a human hand, use the menu at the left of this page (under "Diamond Size on Hand"), or use the "Diamond Information" menu bar near the top of the page.

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Technical - How Much is a Carat?

A carat is a unit of mass used for measuring gems such as diamonds. One carat is 200 milligrams (200 mg). For reference, a typical medicine tablet might be anywhere between 100 and 1000 mg.

People also describe diamond sizes in terms of 'points'. There are one hundred points in a carat. So a fifty (50) point diamond is a half carat diamond.

Actual Diamond Diameters by Carat Weight

This picture shows the (approximate) sizes of various diamond carat weights, for a round (brilliant) cut. The size that these appear on your computer screen will vary depending on how big your monitor is etc... if you want to get a more exact idea of size, pay attention to the 'mm' measurement. This is the diameter (total width) of the diamond, when view from above. Once again, if you are looking for how big these will appear on a human hand, find the appropriate size link under the Diamond Size on Hand links in the left column of this webpage.

How Does Visual Size Vary with Carat Weight?

This is a very important question, because for a lot of people, a two carat diamond does not appear to be twice as big as a one carat diamond. Why is this? It's because the 'diameter' (how wide the diamond is when viewed from above) isn't twice as big for a diamond with twice the carat weight. The reason for this is because of a relationship between volume and area - the easiest way to explain it is to point out that a person that weighs 100 kilograms is almost never twice as tall as a person who weighs 50 kg.

For example, check out the difference between the 1.0 carat and 2.0 carat diamonds. The 2.0 carat diamond has 50% more mass, but its diameter (8.2 mm) is only 26% larger than for the 1.0 carat diamond (6.5 mm). Here's a zoomed in picture to illustrate that difference:

Lifestyle Considerations

A huge diamond is nice and all, but it may not suit all lifestyles. For an active lifestyle, you may want to limit the size of the diamond, and also make sure you pick a ring setting that is as secure as possible. Of course, you can always take the ring off during exercise or work, but every time you take the ring off you increase the chances of losing it, which is to be avoided at all costs!

Save Money with Odd Carat Weights

One tactic which can work in some situations is to choose 'odd' carat weights. For example, if your budget can afford a half carat diamond, look for 0.47 - 0.49 carat diamonds. In some stores, there is a price hike at the 'round' numbers such as 0.5 and 1.0 carats.

Match the Hand Type and Size

A diamond looks bigger on a person with small hands and dainty fingers. Make sure you consider this when buying the ring - for people with quite small, dainty fingers, it is possible to get a diamond that is a little too big to look good (although for some people the mere concept of a diamond being 'too big' seems impossible).

Check out a range of diamond sizes using real photos

One of the best ways to get a feel for diamond size is to look at a few. James Allen has an online tool for finding diamonds where you can select the range of diamond sizes you're interested in. For example, in the screenshot below, I'm look for diamonds between the 0.7 and 30 carats in size. You can click on the image to go try some searches yourself. I've circled in blue where you change the size range you want to search for.

Screenshot of the diamond search tool provided by James Allen.

Size isn't everything!

Ha ha. Well in the case of diamonds, the phrase "Size isn't everything" is often true. There are other things to worry about such as the cut, clarity and colour of the diamond, and even the largest diamond won't look that great if it has a whopping big crack through the centre.