Orange Spoons, Citrus Spoons, and Grapefruit Spoons are basically the same piece just called different names in different patterns. Although, Gorham shows in some of its patterns, both an Orange and a Grapefruit spoon. I could find on Orange spoon in Buttercup and a Grapefruit spoon in Chantilly that both had the same lines, so I suspect one is misnamed. However, some research showed that there may be a piece out there that is the "other" piece that has the decoration continuing from the handle down around the top of the bowl of the spoon. Every source I looked showed them being "out of stock." So, I am thinking, the elusive piece is there, and may very well be in your sliver chest.
Anyway, the spoons were developed to pierce into the pulp of citrus, both oranges and grapefruit. Often the bowl was washed with gold to prevent the acid from the fruit tarnishing the silver.
(Grapefruit Spoon shown in American Beauty by Shiebler 6 inches)
(Grapefruit Spoon shown in Chantilly by Gorham 5 3/4 inches)
(Grapefruit Spoon shown in Alcazar by Durgin 6 1/8 inches)