Article: Understanding MM to Carat Conversion: What You Need to Know

Understanding MM to Carat Conversion: What You Need to Know

When choosing a diamond, size and weight are often top of mind, but they’re not the same thing. While carat refers to a diamond’s weight, millimetres (mm) describe its physical dimensions. The two are closely linked, yet not interchangeable. A 1-carat diamond can vary in visible size depending on its shape, cut proportions, and depth.

This is where MM to carat conversion charts come in. They offer a helpful visual reference to understand how large a diamond might appear at different weights and shapes. Whether you’re selecting a classic round brilliant or a more elongated oval or emerald cut, this guide will help you compare carat weight to millimetre size with confidence.

Explore the chart below for a clearer sense of scale as you search for your perfect lab-grown diamond.

Frequently Asked Questions

Do lab-grown diamonds have the same colour range as natural diamonds?

Yes. Lab-grown diamonds share the same chemical composition and crystal structure as natural diamonds. They are graded on the same GIA colour scale, ranging from D (colourless) to Z (light yellow or brown). This means lab-grown diamonds offer the full spectrum of colours found in natural stones.

What do the different diamond colour grades (D to Z) mean?

The GIA scale rates diamonds from D (completely colourless) to Z (noticeable yellow or brown tint). D-F grades are the rarest and most prized for their icy whiteness. G-J diamonds appear near colourless to most observers, while K-M and beyond show faint colour more visibly. The less colour, the higher the diamond’s value and brilliance.

Which diamond colour grades are considered the best for engagement rings?

The best diamond colour depends on your style and setting. For brilliance and a crisp white appearance, D-F colourless diamonds are ideal, especially for step cuts like emerald or Asscher. Near colourless stones (G-J) can offer excellent value and still look very white, particularly in brilliant cuts and warmer metal settings.

How does diamond colour affect the appearance of different diamond cuts?

Cuts with many facets, like round brilliants, reflect light that can mask faint colour, allowing you to choose slightly lower colour grades without noticeable difference. Step cuts with large, open facets reveal colour more easily, so higher colour grades (D-F) are recommended to maintain a bright, clear look.