I'm new to this forum. I did some search here and I don't see this question. I know how to calculate diamond by weight, color and clarity, but I'm looking for grade.
Color and clarity are grading scales. What type of grade are you referring to? Cut grade is a pretty fickle thing esp with any other cut than rounds. And outside the "excellent" cut grade, I'm sure it gets pretty complicated for rounds too.
There is a standardized cut grading for round and princess cut stones. There are none for fancy shapes such as cushion, pear, emerald, radiant, oval, marquise, etc.
Retail. If you see something you like, give us the information and we'll be happy to help you determine if it's a good stone. Or just tell us what you're looking for and your budget and we can help you find it. May want to start a new thread in Rocky Talk for that though.