Stitching

Stitching is often the weakest link, with many gloves coming apart at the seams (as opposed to the leather). I suspect many companies take shortcuts in the stitching because it saves labor costs and hardly anyone notices the difference. I'm no expert, either. All I know is: nylon thread is better than cotton thread, cotton thread better than polyester thread, thick thread is better than thin thread, double-stitching is better than single-stitching, and welted seams are better than non-welted seams. I've also heard of sneaky tricks in leather products such as using thick thread on the outside but thin thread on the inside where you can't see it. Tight-stitching is better than having big gaps.

You can inspect a glove's stitching in these key areas: palm, wrist, thumb, back of the hand, and velcro strap (if it has one). Beware of protruding seams, loose stitching, and excess material around the velcro strap. These things can cut or scrape a fighter's face in sparring. (It happens even with headgear!) It's especially common when the stitching comes apart around the palm, wrist, and velcro areas. I especially hate when companies print their logo on a plastic material instead of using a fabric label (like Mexican gloves).

Another detail of stitching is how neat it is. Whenever you have double-stitching, you can look closely at the two rows of stitching to see if they maintain the same distance from each other. Usually when it's done by hand, you will see them not look so even and slightly messy. Whereas a machine obviously will look perfect. You can take machine-stitching as a pro or a con. It can be a pro because it looks good. But can be a con if you wanted something more "hand-made". There are many arguments among manufacturers that these machines are so expensive and if your gloves are made that way, it's probably being made by a big factory doing mass production.