Deep buttoning began as engineering. Before foam existed, upholstery was stuffed with horsehair, and hair moves. Pulling the cover down at regular points with buttons held the stuffing in its place, and the diamond pattern between those points was simply what the fabric did when it was pulled that way. The look everyone now wants was originally a solution to a problem.
Setting a crystal into the button came later, from the ballroom rather than the workshop: a bright point that catches candlelight and repeats itself across a whole surface. On a bed it does the same thing at night, and the effect changes as you move around the room.
What our master Indian artisans do here is get the two crafts to agree with each other. The carved surround has to be cut to the exact line the upholstery will meet, or the padding sits proud of the frame and the profile breaks. Carver and upholsterer work to the same drawing, which is why the buttoned panel and the carved scroll meet cleanly all the way round.