The following is a pair of Psalidognathus friendli from Ecuador. I've posted them due to their unusual all purple color throughout. I have seen this species sold in shades of green, greenish-blue, red, gold-ish, black, and various other color combinations of these colors but, have really never seen it in purple. Perhaps, it is unusual for the species. Not sure. Both were collected in 1971. I recently opted to re-spread both as their legs and antennae had been closely pinned tightly against their bodies presumably to save space.
The male is quite a bit larger overall and has much more heavily built mandibles. This species is quite variable in color as beetles go and is nearly as primeval looking a beast as Macrodontia. Judging by their appearance they no doubt move quickly on their long legs and probably have a nasty disposition when threatened.
In my humble opinion, at least as regards the males (size) matters most; with color running a very close second. Large males of this species are not seemingly as prevalent in the hobby as years ago. There seems to be lots of smaller and medium sized ones. So of coarse, when large males come up they are heavily bid on. Color is still quite important and a small to medium sized male with a really bold (popping) color or one with a couple of colors present (bi-color); can fetch some hefty pricing as well.