60s 70s mod colored drip copper metallic luster ceramic coffee mugs

Retro 60s or 70s vintage copper glazed ceramic coffee cups with colored drip glazes in red, green, blue and yellow. These aren't marked, vintage Japan / Taiwan, or handmade pottery?

All six mugs are 4" tall, and all are in excellent condition. These came to us with the metal rack ' mug tree ', also in very good condition, so we're including it as part of the set.

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Item No. k42734