CERTINA DS Quartz, ca. 1990

Opening CERTINA snap-on Backs
Is not that easy. CERTINA snap-on backs are different then anything snap-on I had seen so far. There is a small gap between the edge of the snap-on back that goes around the case back, rather then an opening groove at a specific location.
Please also note the Scotch Tape to protect the case while working with the very nifty Bergeon case back opener.

Please also note that I left a tiny ding on the lower right lug. You will also note that the case is domed below the case back and if you look closely, you notice that this case back is actually already opened. If you do not want to leave any marks at all, take the strap off, then use something like a stack of coins (easy to adjust the height) to support the Bergeon tool, so you will not have to support it on the case which is as already mentioned, not ideal for this watch, because it is domed. I tried to illustrate this in the simple drawing below, so you could spare your older CERTINAs any opening marks: