An OUTSTANDING stamp, XF, Mint, OG, NH, watermarked, 15 cent, Dark Blue, Clay.   Please see scans for centering and the condition of the gum. The SMQ value for a stamp in this condition is $1450.00.  Shipping is free and satisfaction is guaranteed.   I also have outstanding fine crystal items, vintage baseball and football cards, and high-quality unused U.S. stamps coming up for sale or auction on eBay.  Please let me know what you would like to see listed.