* Isle: This is a common and widely recognized diminutive, often used poetically or in place names (Isle of Man, Isle of Wight).
* Islet: This is a more formal diminutive, suggesting a smaller, often uninhabited island.
* Caye: This term is used in the Caribbean for small, low-lying islands, often made of coral.
* Key: This term is used in the Caribbean and Florida for small, low-lying islands, often made of sand.
* Ait: This term is used in England, especially in the Lake District, for a small island or islet.
You can also use little island or small island for a more straightforward diminutive. Ultimately, the best choice depends on the specific context and the desired meaning.