I assume you are a male, since they also have women's sizes. I bought one of these for my husband and he is a big man, usually wearing XXL, but he wanted the XXXL. I think it's to big, but he is happy with it. Now, with the name Deb, I'm obviously a female, also 170 cm, but weigh 59kg. If I was to order this for myself, I would order a small, but would worry if the arms would be too big around above the elbow. The reason I say this, is because, I make my own dive skins out of the same fabric that ladies bathing suits are made from, Lycra spandex. I couldn't find a female pattern, but did find a men's pattern. The size small fits everywhere, perfectly, except the arms above the elbows are much too wide and have to take them in. If you are a man, I think small would fit nicely. If you are female, I would worry about arm size above the elbow. It's hard to tell, by your name, which you are. I often order men's sizes, even though I'm a female, because the legs on ladies tend to be too short. I hope this helps.
Well, thank you .. OK 52 kg is 114 lbs which is the common unit for most sizing.
Yes, I'm a boy. Now I figured that suits in small which rate from 125 lbs wouldn't fit me so they are big to me.
I found one starts from 115 lbs, that's nice. Still searching ..
Good luck for you and your husband, I'm sure you enjoy diving together :) that's wonderful especially if you dive with your love :P