What is the best L-mount macro lens for professional product photography?

Honestly im about to lose my mind with my current setup. Ive been trying to shoot these high-end jewelry pieces for a client here in Seattle and the focus breathing on my adapted Canon 100mm is just killing me, it keeps hunting and by the time I get the shot the lighting has shifted or Ive just lost my flow completely. I've got a huge deadline coming up next Thursday and I cannot show up with these soft-edged results again because the client is super picky about the texture on the gold bands. Im using a Lumix S5II and I just need something native that actually communicates with the body properly without all this glitchy behavior. Its so stressful when youre charging professional rates but your gear feels like its fighting you every step of the way.

I have about 1400 dollars saved up for a new lens but I dont want to waste it on something that isnt tack sharp from edge to edge. I was looking at the Sigma 105mm but then I heard mixed things about the autofocus speed and the Panasonic 100mm is so new I dont know if it holds up for high-end studio work. Does anyone actually have experience with the absolute best L-mount macro lens for professional product stuff that wont let me down in a pinch? I really need to get this sorted before I lose this contract...