What I want to show with this picture are two things, firstly the bar stools and bench as they relate to your table and chairs. The black looking the goods like Jo P suggested. The second is actually a bit of a disagreement with Jo about different timbers. That's something I used to think too but lately I've been seeing different types of timber combined to good effect, like the redder table and chairs here, although I can still understand if this example looks meh to some. Where the timber combos really work is when there are more combined. So if your floor and table legs are different coloured timber and don't really click then introducing a third timber can give you an analogous colour combo with the timbers which works with the contrasting or complementary elements.

I didn't notice the leather @Neryl Hollingsworth! It's a chair-table hybrid it seems. My friend took this at a gallery some where, and we've been trying to track the piece down ever since!

I love the first one! The cement one looks too industrial for my taste.

They are very nice. Where did you see/find these photos originally? Can you contact the person who posted these photos and ask them where they got these tables from? Otherwise I suggest doing a Google search for small round tables and see what appears. You could be lucky and find them online as you search through furniture web sites. Good luck :)