When I was prying out my oyster mushroom spawn at full colonization, I used a metal butter knife that I boiled and cooled with cold tap water.
If you stay along the edges, you should be ok. You will lose a little bit of the whitish color, but if it is fully colonized, it will make a quick recovery in your fruiting chamber.
What are you using for the substrate?
I also was "dunking" my oyster mushroom spawn to get it to fruit, so the water helped to splorp it out.
And tomorrow is the circus! We can go to the circus! I love the circus! We can take this tiny ad: