Diamond size shape weight conversion

Spreadsheet based tool to help convert Diamond Weight in carats to Girdle Diameter in mm for various cut shapes using best fit lines based on average diamond dimensions found here http://d.neadiamonds.com/diamond-carat

Potentially very useful when combined with the following:
Ring metal cost calculator http://www.thingiverse.com/thing:12589
Ring Creation Script http://www.thingiverse.com/thing:12448
Ring Size System Coversion http://www.thingiverse.com/thing:12689
for costing a custom eng