If I under stand correctly, you're just wanting to build a frame to make a table with a granite top? The granite piece would be measured and will probably overhang the frame by about 1" on each side. Plain legs can be made using 2x2's, and the aprons (pieces that connect the legs) can be made using 1x3s or 1x4s. The cross pieces connecting the center of the frame can also be made using 1x3s or 1x4s. Here is a link to a building plan that uses a round top but the frame underneath is also suitable for a square or rectangular top. I hope this helps!
Here's one idea:
Another table to inspire you:
This might help:
Every granite-topped custom kitchen and granite-topped custom dining table my firm has ever designed has had a 5/8” plywood sub-top to spread the load and to keep the granite from cracking. It also is screwed to the legs/framing, as the granite will just sit on top.
Granite is not as homogeneous as it looks.
If you’re working with a granite slab remnant, it is about 3/4” thick and weighs a lot more than we think.
I will look up the weight, after I get this drafted.
My 60x45” blue pearl granite dining room table top (with a 3” drop edge) weighs almost 400 lbs and takes 4 men to move it.
Even though wood is outstanding in Compression calcs, I would not skimp on the framing lumber, nor the diagonal bracing- to mitigate “Racking”.
I think this DiY will help. https://www.hunker.com/13404246/how-to-build-a-table-frame-for-granite