Rare Carat Ideal

All about the Rare Carat Ideal cut grade filter

Karly B. (GIA Gemologist) avatar
Written by Karly B. (GIA Gemologist)
Updated over a week ago

Is Rare Carat Ideal the Newest Cut Grade to Hit the Market?

Lol, no, you aren't going to find RC Ideal listed under the cut grade section on your GIA, IGI or GCAL report, but it would be cool if you could! The Rare Carat Ideal distinction is actually a specific set of criteria that show us a diamond has been exceptionally cut. After all, cut is definitely the most important of the 4C’s.

Our team of graduate gemologists has taken their collective years of experience and training to devise a strict standard for each diamond shape and we’ve packaged it up nicely for you in the Rare Carat Ideal cut grade. We took all of the hard work out to make shopping for your diamond as hassle-free as possible!

So what is the Rare Carat Ideal cut grade?


It's essentially a filter that we set up so you don't have to input all of the ideal specs for a diamond manually. Each diamond shape has a different set of ideal parameters for the cut grade (round only), polish, symmetry, crown angle (round only), depth percentage, table percentage and girdle thickness. When you set the cut grade slider to "Rare Carat Ideal" all of those parameters get set automatically so you'll see beautifully cut and proportioned diamonds right from the start!

Pro-tip: Click the "meets all checks" option on the left side of the search page to filter out any diamond that has an unwanted clarity characteristic like a cavity, chip or knot.

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What are the ideal proportions for each shape?

We've made a handy chart for each shape! (Click on each chart to read more about that specific shape).

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Ideal cushion .webp
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Ideal pear.webp
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I don't know diamond lingo, what do all of those parameters mean?

I'm glad you asked! Here's a quick rundown of the most common diamond proportions that we look at.

  • Cut: This is the most important of the 4C's - it's where all of the sparkle and shine comes from! It takes into consideration the overall design, craftsmanship and appearance. Only a round brilliant currently gets an official cut grade.

  • Polish: This tells us how smooth and shiny the surface is. A high polish grade (Excellent or Very Good) means you'll have a diamond with no visible surface blemishes that could potentially affect the appearance or light return.

  • Symmetry: This tells us how well the facets are formed and aligned. We want a diamond with facets that line up as perfectly as possible so the light can bounce around at all the right angles and bring sparkle to our eyes (Excellent or Very Good).

  • Depth Percentage: The depth percentage tells us how deep or shallow the diamond is cut - measured from the table to the culet. Each shape has a specific range that is considered ideal for the most proportionate diamond and the most sparkle!

  • Table Percentage: The table is the largest facet on the diamond and the one where the most light enters and exits. Again, each shape has a target ideal range so you get just the right amount of light entering and exiting to have a brilliant and sparkly diamond!

  • Girdle Thickness: The girdle is the separation plane between the top (crown) portion and the bottom (pavilion) portion. Having a girdle thickness of Thin - Thick is ideal to ensure there is no wasted carat weight sitting around the middle (too thick) or making it prone to chipping (too thin).

  • Crown Angle: (for rounds only) This measures the top portion of the stone. Keeping it within the ideal range of 33º - 35º is going to ensure the diamond will look proportionate as well as have a good combination of light and dark areas.

Final Pro-tip: Don’t hesitate to reach out to one of our gemologists for help! We can look over any diamond you have found or set up a custom search just for you.

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