You can repolish it with a polishing compound if you just want to increase the gloss.
Here is a kit that is complete except for a variable speed grinder or a low speed grinder. This kit also has our DVD "Glues & Sealers" which shows you how to use the epoxy for repairs and how to repolish the stone with the compound.
For Uba Tuba you want to use the compound for dark granite:
http://www.defusco.com/How-To-DVDs-&-Tool-Packages/c654/p2663/Dia-Glo-Dark-Granite-Complete-Repolishing-&-Sealing-Kit/product_info.htmlGlad to be of service,
Mark