I hope to purchase a large (1.75 carat) Marquise loose diamond on-line in the coming weeks. However, I am trying to determine what/how to calculate length x width, depth, table, etc. for this type stone. In other words, I am very concerned I will miss my target on ''cut'' and will select a stone less than "ideal". Surely, there must be a formula whereby length x widht can be measured to provide maximum appearance, brilliance, etc. Any help would genuinely be appreciated! Here or [email protected].