1940s Case xx steak knives mother of pearl handle

[Zepplin]

Im curious if anyone knows anything about this set. My Dad picked them up this morning for $60.

Knife info as follows.

Unsharpened and appear unused, in like new condition.

Case with the swoopy C
Tested XX Is on the back of wood case itself.

Each knife has thick mother of pearl handles. On the knives themselves is this process patent number 2147079.

The set was apparently sold at Berlines, Fine gifts and cutlery, Seattle WA.
A nice looking decal is attached to the case with that info.

The case is really well built and has some inlaid wood on the top in a cross type pattern.

Any info appreciated. Mostly curious about how many made and possibly the value or a rough estimate. Ebay doesnt show anything.

[BillyD]

got any pics of the stamp and knives?