A PRISTINE 1917 #504 Bottom Block of 6 with Plate Number, 5 cent, Blue, Washington XF, NH, OG.  There is light natural offset on the reverse.  Please see scans for centering and the condition of the gum. The SMQ value for this block in this condition is $330.00.  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.