If the stamp is without grills, it's going to be a 65, 99.99% of the time. And I'm afraid that the only way to know is to have a reference copy in your hand, and then still it's difficult.
I've collected this stamp for over 10 years now, trying to ID the various shades that have been published, but not listed in Scott. I thought it was a good, challenging project for a guy who is red/green color blind!
Your best bet in finding something other than 65, would be with year-dated covers, and the year date should be 1861. The pinks and rose pinks were the first color of this stamp, and were actually printed in August of 1861. Chances are if it's 1862 or later, it's not pink. There are some 1863-printed 3c'ers that look very pink, and they are sometimes listed as pinkish-rose (which is a 65), but would never be certified as pink, because they aren't 1861's.
There are plenty of articles in The Chronicle, which is the periodical for the USPCS (U.S. Philatelic Classics Society), which is a great sub-organization of APS, The colors of the 3c 1861-69 can be found in The Chronicle.
Good Luck! Hope this is helpful, Ray
To DON-- notice I didn't use the word SHADE!!