for the RG DBTY (and I believe silver as well), for diamonds up to .17ct there is a thicker bezel (and wont poke). From 0.18ct you have the thin bezel. I also noticed in store that the thick RG bezel is more "red" than the thin RG bezel.
for the YG and Platinum version, you have always the thin bezel (regardless of the size of the diamond).
From my researches, a size 0.17 with the thin bezel will poke. However you can let them add a basket on the back to prevent poking (however I believe it will cost something).
I have got the 0.17ct in RG (which has a thicker bezel). Advantage is that the diamond looks bigger and does not poke. However it may be less shiny than the ones with the thin bezel. hth
wow this is really interesting and helpful - thank you!!
Unfortunately my passion is YG, so I guess there is no chance for me to get a not poking diamond without adding this "basket""?