"Whoever has ears, let them hear what the Spirit says to the churches. To the one who is victorious, I will give some of the hidden manna. I will also give that person a white stone with a new name written on it, known only to the one who receives it." (Revelation 2.17)
In Rome, the great houses had their clients and dependents who every morning received from their patron food and money for the day. They were sometimes given a "Tessera" which could be a white stone, a wooden or even a metal token of a similar size to a one cent US coin or an English penny.
The Tessera was a token or tally in ancient times which was used like a theatre ticket by which a person had the right to free entry into an event in the Colosseum or to a free meal at a banquet. "The white stone" or the "given Tessera" for the Christian would mean that he or she is given the right to the free spiritual rewards which only Christ can give.
One of the greatest honors in the ancient world was to be victorious at the games and to receive a Tessera. Outstanding victors were given a "Tessera", by the master of the games, conferred upon them special rights. Revelation's Tessera confirms to the Christian that the victorious follower of Christ shares in the future glory of Jesus' reign.