Synthetic diamonds are not that cheap (about 50% of the price of the natural ones), because they are not that easy to make. The large synthetic diamonds are gro

Synthetic diamonds are not that cheap (about 50% of the price of the natural ones), because they are not that easy to make. The large synthetic diamonds are grown in HPHT medium (>2600 degrees C), and even if they are made by a machine, they still grow at an incredibly slow rate (maybe one micron/hour), so you have to keep a huge temperature and pressure for months to get a big one - and maybe at the end it shatters and you just get 3 carat diamonds from it. So the costs are not really paperweight-ready (or maybe you have a few millions to spare for a paperweight). The biggest synthetic diamond data I could find is 60-carat[1] unpolished (10 carat polished). Diamonds are also not really good as a paperweight (one carat is 0.2 grams, a sheet of A4 paper is heavier than a 25-carat diamond). [1] http://www.diamonds.net/Magazine/Article.aspx?ArticleID=53742&RDRIssueID=143 http://www.diamonds.net/Magazine/Article.aspx?ArticleID=5374...