Since no one has chimed in yet, I'll give you my best guess. They could be "Peruvian Purple". They can be very dark, and could appear almost black. Check the photo in the link below, to see if it looks like yours.

Here is a link that might be useful: Peruvian purple potato

Zeedman
Thanks for the response. Our potatohas no resemblance to the Peruvian Purple. Have since been told,from the friend who gave them to us, they might have come from the Philipines.

Jim

OK, that helps; my wife is from the Philippines. Your "potato" could be a yam. Does it look like this?

Here is a link that might be useful: Purple yam (ube)

Zeedman
No it doesnt,sorry. Thanks fo looking. These potatos are a nice small 1-2 inches in diameter with a smooth dark purplish skin and an even a darker interior. Sorry I dont have photo capability.
Jim

What about 'All Blue' Potatos? They are smaller, alhtough I don't think they are quite as dark as you describe.

laree
I found blue potato,blue Kongo on Daves forum. The first picture resembles my black potatos very closely. Thanks for your post. I actually took a potato out into the bright sunkight and it didn't look as Black as I described in my original post.

Jim

i belive its this one Azul)(Black and Blue paul

There are a number of dark blue purple Irish Potatoes (Soloanum tuberosum) Blue Congo ( which goes by a number of other names) Violette du Lac Bret, Négresse, Macintosh Black are among the darkest.
When you mentioned the Philippines, most of us think of purple sweet potatoes (Ipomoea batatas) You may be able to narrow down your selection by size shape and growth habit, but probably will not be able to get a definitive answer.