Bernhard Nickel started making scopes under his own name in about 1936, after leaving Zeiss. The company was bought out by Hertel & Reuss in about the 1980s but they continued putting out scopes under the Nickel name, until the name was bought by the present Nickel concern, which makes very high end (and expensive) scopes but has little to do with the previous business.
I wouldn't think that scope is post-1990. Looking at the style of it, and the elevation and windage adjustments, I'd suspect it is of about the same age as the rifle it is mounted on. Certainly an older-looking scope than the Nickel Supra I have. Both your rifle and scope look to be in excellent order too.
My Brno No 1 was made in 1956 so I assume the scope is from around the same era.
