I'm not at my work box right now so I could only look in my home box. I thought I had a variety of sockets at home, but I guess not much. Mostly Snap-On. With Snap-On, the metrics have a double serrated rings while the standards have a double smooth ring at the base. I did pick up a set of Matco 12 point sockets. It looks like Matco laser etched their standards with red print. I looked up the Matco metrics and they are etched with blue print. I believe Craftsman have been labeling their sockets. With a Google search, it is hard to tell what Mac is doing. I would have to get back to the shop to see what other manufacturers do.
Snap-On standard and metric with a Matco set thrown in:
http://www.bunchobikes.com/sockets.jpg When I started work in the field, one thing we would do so other crews wouldn't steal our tools, was to paint them. It would be easy to find that yellow socket in a sea of green. And the paint actually sticks pretty good. When I got to my current shop, I noticed that someone, long ago had painted the metric impact sockets blue and the standard yellow. Still easy to pick out of the pile.
