This is a British Guiana Stamp, SG 159, the "2" on 24 Cents Green, issued in 1877. 

This one has a line through the old value, effectively crossing it out!  The perfs are short at the bottom.

This wonderful stamp is in Mint Very Fine Condition with its Original Gum, and is valued at L375 in the Stanley Gibbons Catalogue! 

This is a VERY RARE & BEAUTIFUL STAMP!

This item is over $100 USD so I will ship it using Priority Mail in the US, and Registered Mail overseas.  This is to ensure that it reaches you in a safe and timely manner, and includes tracking!