Greengage fruit are identified by their round-oval shape and smooth-textured, pale green flesh; they are on average smaller than round plums but larger than mirabelle plums—usually between 2 and 4 centimetres (1 and 1+1⁄2 in) diameter.

The skin ranges in colour from green to yellowish, with a pale blue "blush" in some cultivars; a few Reine Claudes, such as 'Graf Althanns', are reddish-purple due to crossbreeding with other plums.

[4] Supposedly, the labels identifying the French plum trees were lost in transit to Gage's home at Hengrave Hall, near Bury St Edmunds.

In the Czech Republic, they are known as ringle, in Poland as renklody, in Hungary as ringló,[10] in Slovakia as ringloty, in Slovenia as ringlo, and in Portugal as Raínha Cláudia.

In Portugal, however, they make up a delicacy invented by Dominican nuns in the 16th or 17th century (when confined to their convents) in the town of Elvas, where they are boiled in a sugary syrup several times, over the course of several weeks, to then be preserved whole in syrup or dried, coated in sugar and eaten either with a local dessert, sericaia, made from eggs, sugar, milk, cinnamon and flour or eaten with rich cheeses.