I'm looking to get some bowl gouges and don't want to mortgage my soul. I have a lot of spindle turning tools and I have even made a couple out files for special purposes. I was looking at the Yellowhammer bowl gouge set. Seems to be reasonably priced and would be adequate for my needs. I have a three Robert Sorby carbide tipped tools. They work ok but my biggest complaint with them is the round shaft. They have a tendency to twist. I'm going to buy some replaceable carbide tips and build my own out of 3/8" cold rolled steel square stock. I might build one out 5/16" also. I'm very familiar with working with machine work and steel so that's not a challenge. When I was looking at the replaceable tips I could figure out what the square and round cutters were for but what is the diamond shaped one used for? Can it be used for a parting tool or does it have another purpose? Thanks, Jim