TL;DR: Windowing in an emerald cut diamond is a see-through effect where light passes straight through the stone's centre rather than reflecting back, making that area look dull, glassy, or washed out. It's caused by pavilion proportions that are too shallow, and it's worth checking for specifically since it isn't captured by the standard certificate grades.
Why Emerald Cuts Are Prone to This Specifically
Emerald cuts are step cuts, with broad, flat facets running in parallel rows rather than the many small triangular facets of a brilliant cut. This faceting style produces a distinctive hall-of-mirrors optical effect at its best, but it also means there's less opportunity to disguise light leaking straight through the stone if the proportions aren't right.
What Causes Windowing
A pavilion (the lower portion of the stone) cut too shallow allows light entering from above to pass straight through the bottom of the stone rather than reflecting back up toward the viewer. In an emerald cut, this shows up as a visibly duller, more transparent-looking area, usually toward the centre of the table.
Why the Certificate Doesn't Catch This
Because there's no standardised cut grade for emerald cuts the way there is for round brilliants, a certificate showing strong colour and clarity grades tells you nothing about whether the specific stone shows windowing. This is purely a proportion issue, assessable only by actually looking at the stone.
How to Check for Windowing
Look at the stone under normal lighting, ideally via video showing the stone from multiple angles rather than a single static photograph. A stone with even light return across the table has no obvious dull or overly transparent patch; a stone with windowing shows a visibly duller or more see-through area, usually centred.
Windowing Isn't Always Severe
Minor windowing is common even in reasonably well-cut emerald cuts and isn't necessarily a dealbreaker — the question is one of degree. Severe windowing, where a large, obviously duller patch dominates the stone's appearance, is worth avoiding; minor, subtle windowing is a matter of personal tolerance.
Assessing Emerald Cuts at À Vie Diamonds
We provide video of every emerald cut stone specifically so windowing can be properly assessed before you commit. Get in touch to discuss emerald cut options.
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Frequently Asked Questions
What is windowing in an emerald cut diamond? A see-through effect where light passes straight through the stone's centre rather than reflecting back, making that area look dull or glassy, caused by pavilion proportions cut too shallow.
Does a diamond certificate show whether a stone has windowing? No — there's no standardised cut grade for emerald cuts, so windowing can only be assessed by viewing the specific stone, not from certificate figures alone.
Last reviewed: July 2026 · À Vie Diamonds