Hi Lee
I used Corel Draw first then ran it through V carve pro to generate the toolpath , With the stone I use Diamond encrusted tooling ( DK HOLDINGS LTD )
Used a 6mm endmill for roughing and then a 3mm ball nose for final finish all on a Feedrate of 50 and a Plunge rate of 2.0 and that worked for the Slate / Granite / Sandstone / and Marble. It can be a bit messy though
Hope this helps Bud
Pete