The best girdle thickness is thin, med to slightly thick according to the advanced tutorial. You can find this at the top of the page under knowledge. Click on that and to the left you will see a list of all the parts of a diamond to find any info you need. This way you have an instant source of knowledge at your fingertips which will be a huge help with you " homework!" Also you can use the search tool at the top of the page to look up any other info you need. Hope this helps.