The Diamonds were one of the most popular vocal groups of the 1950s, a quartet of Canadians best known for their hit "Little Darlin'," which reached the #2 spot on Billboard's singles chart in 1957. Tom Hanks is an American actor, producer, writer, and director best known for winning consecutive Best Actor Academy Awards (for Philadelphia in 1993 and Forrest Gump in 1994). Contrary to the rumor reproduced above, however, there is no familial connection between The Diamonds and Tom Hanks.
The lead singer of The Diamonds when they recorded hits such as "Little Darlin'" was Dave Somerville, a native of Guelph, Ontario, who was born in 1933 and died in July 2015. (Somerville left The Diamonds in 1961, although from the late 1980s onwards he performed occasionally with original members of the group.)
Tom Hanks' father, Amos Mefford Hanks, was born in Glenn County, California, in 1924 and died in 1992. Amos Hanks, according to various biographies, was something between an "itinerant cook" and a "restaurant chef."
None of The Diamonds, either the original group or the replacement members, bore the surname Hanks or is known to be directly related to Tom Hanks the actor.