90 in a square hallmark. Who marked their silver like this?

[bosetunes]

I have a set of silver ware, sort of a deco pattern, that is marked on the blades Kruger- J Rainer Guarantie Solingen and then all the solid silver pieces simply has the number 90 in a square. What country did this?
Please help!

Also I am confused by this site- It said photo shy was where you would post queries without a photo and the top of this page says 2 photos required???

[Doos]

Apparently Germany does, as Solingen is German.
Here in Holland we do that aswell.

It is an indication of the thickness of silverplate.
What it really means is that it has an equivalent thinkness to 12 couverts (12 spoons and 12 forks) that have been coated with 90 grams of silver.