Because Asscher cut diamonds are much less common than round brilliants, many retailers won’t have any in stock. You are much better off buying fancy shapes like this online because you’ll have a much better selection in your target color, clarity and carat weight so you can assess the shape and cut quality and pick a really beautiful diamond that’s a good value too.
You’ll be able to select a better Asscher cut diamond if you buy it loose rather than already set into an engagement ring.
It’s important to rely only on diamond grading reports from GIA or AGS, the world’s most respected diamond grading laboratories. You can’t rely on the grades from other labs to be equivalent.