MCM vintage pottery tumblers or short squat mini pots / vases, minimalist art ceramic

These little tumblers or vases look like mid century modern German art pottery to me, but I'm not an expert on the vintage Germany marks, and I'm not even sure I have the mark right side up in the photos! Looks like a small logo stamp, and either 59 or a 65 to me. So I think these are probably mid-century vintage, as they look.

This is a set of six 3" tall vases or tumblers, brown with an orange-red X border design, clean white interiors. Nice chunky weight to them, and all in very good condition without damage or wear.