The Five O'Clock Spoon is longer than the Four O'Clock Spoon at 4 3/4 to 5 3/8, but shorter in length at 5 to 5 5/8 inches than the regular teaspoon, usually 5 7/8 to slightly over 6 inches. Although, this spoon can also to be used when coffee is served in the late afternoon, it has an identity crisis. You will see Five O'Clock spoons referred to as "Youth Five O'Clock spoons" which I think indicates their shorter size fitting into a youth's place setting. Also, they are called "Five O'Clock Souvenir spoons". The souvenir spoons usually have some type of design engraved on them - a city, world's fair, a state, etc. These are examples of true Five O'Clock Spoons.
Mythologique by Gorham (5 inches)
Montclair by Gorham (5 1/2 inches)
Misc Floral Pattern (Golden Rod) by Baker Manchester (5 inches)
ALS5 Lily by Alvin (5 5/8 inches)
Love Disarmed by Reed & Barton (5 5/8 inches)