jewelers loop

Radio Shack has an illuminated pocket microscope that works well.
It goes from 25x to 150X (that is just a remembered guess) but it works great. (if you can find the tip of the stylus!
I use a piece of paper and have the edge next to the stylus, so I can find the edge and then move up to the stylus!
Otherwise you risk banging into the stylus when searching for it at over 100x

Shure says that you MUST use a microscope with a least 200X magnification, and that it must have two side lights to reflect off the two sides of the stylus under examination. Also required are photos of new, worn, and extremely worn stylii of the same profile as the one you're looking at. The stereo shop where I purchased cartridges many years ago had the correct equipment. The manager of the shop also examined all new cartridges and replacement stylii to make sure that the stylus was aligned correctly on the cantilever. He found many that were misaligned, which he returned to the suppliers. His suppliers told him that he returned far more new stylii than any other retailer. Obviously, the rest of the retailers did NOT have the correct equipment and/or the experience to use it correctly.

I've read that checking the stylus for wear warrants a special stereo microscope.

However, for everyday (record to record) stylus inspection I use a 20X loop mounted on a stand. It is great for checking the stylus and cantilever for dirt. I position the loupe so it is the right height to check the stylus with the tonearm in its rest. So simple that I check after each side.

Got mine off ebay, below is a link. I have no affiliation with the product.

20X loupe on a stand

I use an old scope I "borrowed" from the Boatny lab when I was in college and I forget to take it back...

Jimrick makes a VERY good point regarding the need to have either experience to draw on or pictures to look at regarding a worn and unworn stylus. I'd wager that the vast majority of folks would not be able to tell whether the stylus was worn or not, even if they had the appropriate optics to see it clearly.