I was able to get like a crit or something. If you shoot the rocks right as it hits you, you can collect all the gems instantly and get 560 every time. Although you risk getting hit so...
Veteran shoot rockers call this the "Ivan maneuver". Ivan did not live long.
(This happens because you collect all the gems before they have a chance to spread out. 1024 bytes meant no space to add a delay before the gems become collectible)