I'm growing a berry ryder also and was wondering the same thing.
In your situation, however, I would imagine that lowering the temps to induce bluing in the ryder will probably negatively affect the other two plants. If all 3 are healthy and thriving, I don't know if i would want to de-rail that by trying to bring out the blue in the berry ryder. If they were all berry's then it would different.
My temps have been between 71-79F for her entire life (around 7 weeks) and I don't have bluing. Up close, I noticed a few hairs with blue tint but that is it.
If you decide to lower the temp, which I believe they recommend during the dark period, please post pics and updates!
Good luck brother.
Also, can you post a pic of the berry ryder? Mine is slightly younger than yours. Thanks!