What is a suffix for shimmered?

There isn't a common, direct suffix for "shimmered." "Shimmered" is already the past tense and past participle form of the verb "shimmer."

However, you could use a suffix to create a related word, such as:

* Shimmering (adjective): Describes something that is shimmering.

* Shimmeringly (adverb): Describes how something shimmers.

Let me know if you had a specific type of word in mind, and I might be able to give you a more specific answer!