The Combine Ring's icon on a monitor's screen is represented by a dark blue ring.
When picking up up the Combine Ring, its icon appears to the bottom of screen and stays there until the player receives damage that causes Rings to be dropped. At that point, the player only loses a single, larger Ring containing all the Rings player has collected at this point. If the player re-obtains this single Ring, the player regains all the Rings they lost from the damage they took, while the Combine Ring feature disappearing from the screen. If the player does not obtain the large Ring within a few seconds though, it bursts into the usual shower of regular Rings when taking damage.
↑"Combine Ring is silver instead of gold. It combines into one all the Rings you lose if you touch a Badnik or hit dangerous terrain. If you grab that one Ring, you regain all the Rings you have collected before." - American instruction manual of Knuckles' Chaotix, page 18.