Identifying Fat Vs. Gristle

In packaged raw cuts of red meat, sometimes it can really be hard to differentiate fat from gristle. They both appear white against the red of the meat.

I've been so disappointed by many packages of short ribs and sirloin steak that appeared to have plenty of fat on them, when actually it turned out to be inedible gristle.

I'm trying to learn better how to identify gristle through the plastic wrap, so I don't waste money on bad cuts. It's not easy!

On this cut below, it even cooked up nicely and looked like mostly fat:

Grassfed sirloin steak with roasted beef marrow and sea salt flakes

However, when I actually began to bite into it, I realized that there was a layer of gristle (or silverskin) right under the fat, as well as on the bottom of the cut too. You can see them both if you look closely!

So, how could I have known this sirloin was mostly gristle and not fat?

I'm going to try to learn better how to analyze raw, packaged cuts in plastic wrap.

Here's two photos of a beef short ribs, from either side of the package:

In the first photo, I think I can see two layers of gristle or silverskin in the middle, with a small layer of red in between. The silverskin appears a little more pinkish/silvery than the yellow/white of the fat above.

In the second photo, the top and bottom appear to be fat, but in the middle there is some pinkish stuff which is probably gristle.

I'll report back once I've cooked it up and can tell for sure!

Edited to Add: OK, I've cooked these up. They were actually two thin riblets on top of each other. The pinkish area in the first photo was actually bone. The bottom part of the second photo was mostly bone and gristle. The fatty part on the top of the second photo was pretty good, but there were layers of silverskin on the top of the fat and below it. Overall, I wasn't too pleased with the fat content. Beef short ribs in general haven't been fatty enough!