The 10 Rupees Postage stamp depicting Mahatma Gandhi issued by India in 1948 is one of India's most famous stamps. Due to change of political circumstances (Before the stamps were issued, Gandhi was assassinated), its actual sale could not take off. A set of 100 of these stamps were overprinted with the word "Service" and provided only to the Governor General of India (Mr.C.Rajagopalachari) for his official use. However, C Rajagopalachari is said to have distributed 17 such stamps to his friends/ relatives, later. This "Service" overprinted stamp is one of India's costliest and rarest stamps.
The above picture was taken from the exhibit at Indipex 2011, International Stamp Exhibition held recently at New Delhi. This sheet is supposedly one of the 2 known sheets which exists and this sheet belongs to Department of Posts, Government of India.