Buying new stones and found a company that has stones and replacement paper for when the diamonds are worn out. TBH, I hadnt even thought to look at the construction of a stone but many look like they are manufactured the same but there is no option to replace the grit. The company is a US Ski and Snowboard team supplier or so they say. I currently have the Racewax diamond stones and have no experience with other brands, Here is the link and looking forward to your opinions.
Hone Stones
Hone Stones