How do I judge the quality of countertop work?

By the time the saw makes its first pass down the slab, the color and veining are already committed. Choosing a fabricator for a countertop in Tulsa, OK comes down to what gets checked before that cut, and the checks here run stricter than countertops tulsa aedreams would list for a first visit. The same habits carry past install, when the finished top gets measured against what was agreed.
Look at the actual slab

Color and veining shift from slab to slab and across a single slab, so a small sample overstates how even the stone will be. Walk the yard and look at the piece that will be cut, whether granite, marble or quartzite. Mark the areas that must land on the sink run and the visible faces. A remnant can suit a vanity or an island, but it gets the same viewing.
Ask for the shop drawing

Before templating is treated as final, the shop drawing should show seam placement, overhangs, edge profiles, cutouts, and how the veining runs across each piece. A drawing with only outside dimensions leaves those decisions to whoever runs the saw. The fewest seams is not automatically the strongest layout. A joint placed with the sink cutout and the span in mind can be the sounder choice.
Get the agreement in writing
The paper should name removal of the old top, plumbing disconnect and reconnect, repairs to walls and cabinets, seam layout, care instructions, and both the workmanship warranty and the product warranty. Every missing line turns into an argument on install day.
Judge seams and edges by hand
A well made seam is tight, flat, and color matched. It may still show up close, and a visible seam is not proof of poor work. Drag a fingertip across it and feel for a ridge. An eased edge, a bullnose or a waterfall edge should feel the same along the full run, with no chips, wavy sections, or dull spots.
Check overhangs and cutouts
Support under an overhang depends on the material, the thickness, and the overhang distance, and it follows the manufacturer's or fabricator's guidance. Thicker stone alone does not settle it. Cutouts should match the sink and appliances actually on site, with rounded inside corners and smooth, clean edges. Set the sink template into the opening before anything is glued.
Inspect in side light before sign off
Switch off the overhead fixtures and rake a strong lamp across the surface from the side. Scratches, lippage, and polish problems show up that flat light hides. Late sun through a west window anywhere in Tulsa County does the same job. Walk the whole top, mark anything found with tape, and settle it before the final payment.