I don't think body carves give a chance for gem drops, but capture does. You can still get gems from killing the monster by carving the tail and rewards for breaking body parts though. Just look at the monster hunter wiki for carve rates.
I'm pretty sure I've heard Brachy is a 2% carve and 3% cap, so it seems pretty equal I've also heard Jho's cap and carve rate are both 4%, so it's better to kill him --- Death is the solution to all problems. No man - no problem. ~Joseph Stalin
Zinogre/Stygian Zinogre: kill them because you can actually carve the emeralds from them Nargacuga: You can carve from its body moonshards from lucent and mantles from all of them
Silver Rathalos/Gold Rathian: capture as you cannot carve mantles from the body; you also want to cut the tail and break the face
In Freedom Unite, most monsters you'd be fine just killing them, there also seemed to be more missions where you'd have a chance getting the gems from quest rewards. But now in 3 Ultimate most monsters you need to capture because that's your best chance or you can't carve from the body and/or because there's almost no chance of receiving them just from quest rewards.
Also, the top row is for monster parts and the bottom row is for bones, decoration jewels, and wyvernclaws/wyvern fangs. Armor stones can appear in bow for quest rewards. --- GT:RPGamer13 PSN: RPGamer13
I'm pretty sure I've heard Brachy is a 2% carve and 3% cap, so it seems pretty equal I've also heard Jho's cap and carve rate are both 4%, so it's better to kill him
2% carve x3 (3 - 6 depending on tail and Felyne Carver) ... vs. 3% cap x1
Kill. Only capture if the body doesn't have a gem (e.g. Rath).
But you can get multiple gems in the rewards. So wouldn't that mean cap is better?
It's possible to carve multiple gems too. On a Los Ruby run I had Felyne Carver [Hi] proc on the tail and got two rubies from it, got a face break ruby and a capture ruby. Random is random (is random).
I have a first world problem now since I only needed one ruby and now I'm looking at other things to use them for...