About Diamond Size Charts
Diamond Size Charts was created to answer one of the most common, and let’s face it misunderstood, concepts when it comes to diamonds: What does this diamond measure like in milimetres, and vice versa.
Carat weight is often treated as if it tells the whole story. It does not. Carat is a measure of weight, not visible size.
Two diamonds with the same carat weight can have different millimeter measurements, different proportions, and a noticeably different face-up appearance. That difference matters when comparing stones, choosing a setting, matching side stones, or trying to understand what a diamond will look like on the hand.
DiamondSizeCharts.com brings those details together with shape-specific size charts, visual guides, and diamond calculation tools built for practical comparison.
Built With Diamond Trade Experience
Diamond Size Charts is not a hobby project or a collection of generic copy pasted measurements from random sources. The site is created and maintained by members of the diamond and jewelry trade, including a GIA Graduate Gemologist. That trade background shapes how we approach diamond size: not as a single fixed number, Our focus is on relationship between carat weight, millimeter dimensions, shape, proportions, and visual spread. Our goal is to give you practical diamond size references that reflect how diamonds are actually compared in real life situations.
What You’ll Find On This Site
Our site focuses on size charts, for both common, and less common niche diamond shapes that helps convert ct to mm, and mm to ct at ease. In addition, we include on-hand visuals, and helpful info about each specific shape’s unique aspects, ideal length to width ratios, ideal depth and table, and more.
You can use the site to:
- check typical millimeter ranges by shape and carat weight
- compare how different diamond shapes face up
- estimate carat weight from diamond measurements
- understand length-to-width ratio and proportions
- visualize approximate diamond size on the hand
How Our Charts Are Developed
Our charts are built around shape-specific average millimeter ranges for each carat weight. Diamond size cannot be represented accurately by one universal methodology. A round brilliant is usually described by its diameter. Square shapes, such as princess and Asscher cuts, are described by length and width. Elongated shapes, such as oval, emerald, pear, radiant, and marquise diamonds, are described by length and width as well, but their depth is also part of how millimeter dimensions relate to carat weight.
For example, a marquise diamond’s visible size is often discussed through its length and width, but its carat weight also reflects how much depth the stone carries. Two marquise diamonds with similar face-up measurements can weigh differently if one is cut deeper than the other.That is why each chart on DiamondSizeCharts.com is specific to its diamond shape. The purpose is to present an intelligent approximation of the millimeter range one could expect for that shape and carat weight, using average measurement relationships rather than a single universal conversion.
We do not publish our internal formulas or full reference process, but the charts are built around the practical relationship between carat weight, diamond shape, length, width, depth, and average face-up size. For any individual diamond, the exact measurements listed on a grading report should always be used as the final reference.
Tools And Visual Guides
In addition to our charts, DiamondSizeCharts.com includes tools created to aid in different ways. Our calculators and comparison tools can help estimate carat weight from millimeter dimensions based on specific input, or compare different shapes, while gaining a better understanding of how proportions affect face-up size.
Some pages also include visual size references and on-hand comparisons. These are designed to help users understand scale and appearance, not to replace measurements. A diamond’s appearance can vary depending on finger size, setting style, camera distance, lighting, screen size, and the proportions of the individual stone. For that reason, visual guides should be seen as an aid.
Accuracy And Ongoing Refinement
Our site was built to be one of the most accurate and practical diamond size references available online. Our charts are developed around shape-specific average measurement ranges, not generic one-size-fits-all conversions. That distinction matters to us..
At the same time, no online chart can guarantee the exact measurements of every individual diamond. Two stones with the same shape and carat weight can still have differences due to depth, outline, girdle, and cutting style. That is why our charts are intended to show reliable typical ranges, while the measurements on a grading report remain the final reference for a specific stone.
We continue to refine the site with that standard in mind: high-accuracy, and full transparency of what can and cannot be achieved to perfection.
Contact Diamond Size Charts
Have questions or suggestions about our diamond size charts? Let us know using the contact form below.