We've black ginger which is purplish-black in color. It will workout for you. Make it grind and pour in a big bundle of papers.... it will sink down as much as it can till the juice sucked by papers and you can see its impression (color) on all pages. There is no wonder as its color itself is dark purplish-black. When you make it dry, you will get pure black powder. I think this would be workout for you guys.
If required, email me asap: nallapasupu@rediffmail.com
Limited stock. Next Harvest will available after one year only (2014). So make your deal asap.!!!

Sellers of Turmerics & Gingers
nallapasupu@rediffmail.com