The phrase "astonishing example" is correct and usable in written English.
You can use it to describe an example that is surprising or impressive in some way.
Example: "The scientist presented an astonishing example of how climate change is affecting polar bear populations."
Alternatives: "remarkable instance" or "impressive case".
To reporters, this was a particularly astonishing example of an already controlling White House run amok.
Atlanta's political and corporate culture is brash and meritocratic; some of its top businesses CNN is the most astonishing example—were unheard of 15 years ago.
Valentino had earned the right to take it easy for the next 600 years; instead, he sets an astonishing example of resilience, compassion and charity.
Two days ago, Martin Fletcher, a former foreign and associate editor of the Times, emailed me with a truly astonishing example of Mail Online misbehaviour.
It was an astonishing example of a musician playing way out of his skin – and one who had never been in Ellington's front rank of star soloists.
The most astonishing example was a woman who quit her job, gave birth to two children, found another job, and finished the Morning MBA programme with the rest of the cohort.
And we are treated to astonishing examples of open-minded intellectual honesty, arguments from evidence and cleareyed reporting.
"The three women who are taking part in this campaign are astonishing examples of the kinds of dedicated people that will be worst hit in their inability to fight for their services and the people they serve".
The goal of this paper is to show that the Fučík spectrum is one of the most astonishing examples of the latter type.
The video showed astonishing examples, not just of individual joy and dramatic accomplishment, but also of attitudinal transformation -- if I can do this, then I can do anything.
"The material that Bradley Manning is alleged to have leaked has highlighted astonishing examples of U.S. subversion of the democratic process around the world, systematic evasion of accountability for atrocities and killings, and many other abuses," he wrote.
