Diamond Carat

Understanding Diamond Measurement

Diamonds are measured in carats, which indicate their weight, not their size. This means that a diamond with a higher carat weight will be heavier, though not necessarily larger in size.

How to determine carat size

A carat, the standard unit for measuring diamonds, is equivalent to 0.2 grams. Each carat is further divided into 100 points, so a 0.25-carat diamond is equal to 25 points or a quarter of a carat. The size of a diamond relative to its weight is a key factor in determining its value and appeal. For instance, a well-proportioned 1-carat round diamond typically has a diameter of about 6.5mm, while a 1.5-carat measures around 7.2mm, and a 2-carat diamond is approximately 8mm. Each diamond shape has unique ideal dimensions that influence its brilliance, as these proportions are designed to maximize light reflection.

Understanding Diamond Value Per Carat

When purchasing a diamond, it’s essential to evaluate carat weight and cut quality together. A larger diamond with a lower cut grade may look smaller or less brilliant than a diamond of the same weight that has been expertly cut.

Key Factors to Consider

When purchasing a diamond, it’s essential to evaluate carat weight and cut quality together. A larger diamond with a lower cut grade may look smaller or less brilliant than a diamond of the same weight that has been expertly cut.

Diamond Carat Size Chart

Carat Millimeter
0.25ct 4.00mm
0.50 ct 5.2mm
0.75ct 5.8mm
1.00ct 6.55mm
1.25 ct 7.00mm
1.50 ct 7.2mm
2.00 ct 8.0mm
3.00ct 9.2 mm
Circle Diamond
Carat Millimeter
0.25ct 3.3mm
0.50ct 4.3mm
0.75ct 4.8m
1.00ct 5.3mm
1.25ct 6mm
1.50ct 6.15mm
2.00ct 6.8mm
3.00ct 7.8mm
Circle Diamond
Carat Millimeter
0.25ct 3.65 X 3.58 mm
0.50 ct 4.7 X 4.4mm
0.75ct 5.78 X 4.76mm
1.00ct 6 X 5.2mm
1.25 ct 6.6 X 6mm
1.50 ct 6.8 X 6.4mm
2.00 ct 7.3 X 7.2 mm
3.00ct 8.53 X 8.11 mm
Circle Diamond
Carat Millimeter
0.25ct 5 X 3 mm
0.50 ct 5.2 X 3.88 mm
0.75ct 5.89 X 4.25mm
1.00ct 6.5 X 4.8mm
1.25 ct 7.3X 5.3 mm
1.50 ct 7.6 X 5.5mm
2.00 ct 8.4 X 6.2 mm
3.00ct 9.16 X 7.21 mm
Circle Diamond
Carat Millimeter
0.25ct 5.69 X 3.43 mm
0.50 ct 6.8 X 4.45 mm
0.75ct 8.1 X 4.99mm
1.00ct 8.8 X 5.7 mm
1.25 ct 9.5 X 6 mm
1.50 ct 9.7 X 6.2mm
2.00 ct 11.2 X 7.15 mm
3.00ct 12.15 X 7.42 mm
Circle Diamond
Size Details
0.25ct 5.12 X 3.41 mm
0.50 ct 6.3 X 4.4 mm
0.75ct 7.35 X 5.07 mm
1.00ct 7.7 X 5.6 mm
1.25 ct 8.4 X 6 mm
1.50 ct 8.7 X 6.4 mm
2.00 ct 9.7 X 6.8 mm
3.00ct 10.89 X 8.07 mm
Circle Diamond
Size Details
0.25ct 3.82 X 3.49 mm
0.50 ct 5.3 X 4.2 mm
0.75ct 5.67 X 4.37 mm
1.00ct 6 X 4.9 mm
1.25 ct 6.8 X 5.49 mm
1.50 ct 7.1 X 5.8 mm
2.00 ct 8 X 6.4 mm
3.00ct 9.35 X 7.08 mm
Circle Diamond
Size Details
0.25ct 3.3 mm
0.50 ct 4.3 mm
0.75ct 4.8 mm
1.00ct 5.3 mm
1.25 ct 6 mm
1.50 ct 6.15 mm
2.00 ct 6.8 mm
3.00ct 7.8 mm
Circle Diamond
Size Details
0.25ct 6.54 X 3.27 mm
0.50 ct 8.4 X 4.2 mm
0.75ct 9.53 X 4.83 mm
1.00ct 10.4 X 5.2 mm
1.25 ct 11.65 X 5.6 mm
1.50 ct 12 X 6 mm
2.00 ct 13.4 X 6.5 mm
3.00ct 14.02 X 7.48 mm
Circle Diamond
Size Details
0.25ct 3.96 X 4.11 mm
0.50 ct 5.5 X 4.6 mm
0.75ct 6.41 X 5.79 mm
1.00ct 6.8 X 5.8 mm
1.25 ct 7.8 X 6.6 mm
1.50 ct 8 X 6.9 mm
2.00 ct 8.8 X 7.5 mm
3.00ct 9.29 X 9.48 mm
Circle Diamond

Pro Tips

Setting Style

Another key consideration is the setting style, as diamonds placed in a delicate or thin setting often appear larger than those set in a thicker, more substantial setting.

Finger Shape and Diamond Appearance

When choosing a diamond, it's helpful to take the length and width of your ring finger into account. A diamond will typically appear larger on longer, slimmer fingers than on shorter, wider ones. For those with shorter fingers, diamond shapes like marquise or pear can create an elongating effect, making the fingers look more slender.

Smart Pricing Tips for Diamond Buyers

For those working with a tighter budget or seeking better value, a helpful tip is to consider diamonds that are slightly under popular full carat weights, such as 0.40, 0.90, or 1.75 carats. These diamonds, being just shy of the most desirable carat sizes, are often priced more competitively. For instance, a 0.90-carat diamond is generally less expensive than a 1.00-carat diamond, and visually, the difference in size is hard to notice

Impact of Diamond Shape on Appearance

Consider the diamond shape, as certain shapes can make smaller carat sizes appear larger. For instance, the marquise and pear shapes often look bigger because of their elongated cuts.