The whole colors thing when it comes to steak and burgers never did me any favors.
I’m color blind.
Having had jobs cooking many steaks at many restaurants, I’ve always gone by the feel of the corner of the spatula against the meat. The less squishy, the more done it is.
I rarely had a steak or burger get sent back to me.
Good rule of thumb: you can always cook it more, but you can’t de-cook it.
When you're cooking a steak or burgers, or even chicken breasts for that matter, you don't see what color the inside is until after you serve it and your guest starts eating.
So you can't go by color when you're cooking, unless you want to serve a sliced-up steak. Being color-blind is no hindrance to cooking a great steak.
When cooking steak or chicken on the grill I always, ALWAYS use an instant-read thermometer and take the internal temperature of the food I'm cooking. For Rare, pull it off when the middle hits 125. Medium rare, 130. Medium, 135. I don't cook steak any more than Medium.
Once you hit your target temperature, remove and let the steaks rest for 10 minutes. As you let the food rest, there will be some carry over cooking to hit the final internal temp of 130 for rare, 135 for medium rare, and 140 for medium.
Chicken breasts come off the grill at 165. Baked potatoes, 195.
There are fancy Bluetooth thermometers that have multiple zone reading, and can cost upwards of $200. But this is what I use, and it's under $20 on Amazon: