How do you get the 7th chaos emerald in sonic rush?

You don't get the 7th Chaos Emerald in Sonic Rush. The game has six Chaos Emeralds, and they are all located in different stages.

Here's a breakdown:

* Emerald 1: Found at the end of Stage 1 (Ocean Palace)

* Emerald 2: Found at the end of Stage 2 (Iron Fortress)

* Emerald 3: Found at the end of Stage 3 (Sky Rail)

* Emerald 4: Found at the end of Stage 4 (Lost Island)

* Emerald 5: Found at the end of Stage 5 (Lava Reef)

* Emerald 6: Found at the end of Stage 6 (Meteor Base)

Once you collect all six Chaos Emeralds, you unlock the ability to transform into Super Sonic or Super Blaze in the final stage, Final Rush.

Let me know if you have any other questions about Sonic Rush!