archipelago granite china tea cup and saucer

Archipelago granite china tea cup and saucer. It also says RKM on the bottom. I do a lot of estate auctions and find a lot of unique items. Growing up my family was older as my parents waited years to have me. They were married in 1941 2 weeks before they bombed Pearl Harbor. They waited over 20 years for me! So, a lot of items come easier to me having such older relatives growing up. This one I can't find anything on the internet as to who made this item. Does any one know anything about this item? I tried google and nothing at all comes up.