This is based on a meta thing. The author said that 'Not just anyone gets a model sheet' implying that characters who do will have more appearances in the future. Now, both Cinna and Beryl have one, signifying that they will return at some point, or in other words, they would be brought back to life in some fashion.
Tied to above. As he was a target for Topaz and especially since Topaz declared that 'It's not over', Hema will have double incentive to do something like this: make sure Topaz is kept out of his life by restoring Beryl, and ensure that the knowledge of what brought Beryl back to life could be used to bring back other shattered gems. This will give comfort to many grieving gems who lost their loved ones during the war.
Hemmi and Mite still have some sort of grudge against Hema. When Topaz returns, she'll learn about said grudge from some source, and attempt to recruit them to help her carry out her revenge. They will agree, on the condition that they watch him get shattered. They will set things up so he is framed-up again but this time, nothing could point to either of them.
Tied to above. This will convince Topaz to abandon her plans for revenge and flee to a different colony with Beryl where they spend the rest of their lives living together
