The term diamond operator is quite popular: Searching Google for " diamond operator" java yields 78.300 results and Stack Overflow has its own diamond-operator tag.
The Java Language Specification, Java SE 8 Edition, section 3.12 Operators doesn't list <> as an operator though. Section 15.9 Class Instance Creation Expressions refers to it as the diamond form. A diamond operator is not mentioned in this document.
Is the term diamond operator correct? I don't see why you would call this an operator - it's just an empty type argument list after all? Does it make sense to use this term?