2 added some information on behalf of Yvonne's comment.
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Made a design for a gaming service some years back. The bar below indicated ranks in a modified Elo ranking system. The design scheme was inspired by karate belt colors. The color blocks were displayed near the profile picture of each ranked member. White [new beginners] to black [experts]. I haven't included any theory, but I just thought you should have the input.  
EDIT: On the index page you saw the whole rating range which, I believe, helped the understanding of the colors.

mockup

download bmml source – Wireframes created with Balsamiq Mockups

Made a design for a gaming service some years back. The bar below indicated ranks in a modified Elo ranking system. The design scheme was inspired by karate belt colors. The color blocks were displayed near the profile picture of each ranked member. White [new beginners] to black [experts]. I haven't included any theory, but I just thought you should have the input.  

mockup

download bmml source – Wireframes created with Balsamiq Mockups

Made a design for a gaming service some years back. The bar below indicated ranks in a modified Elo ranking system. The design scheme was inspired by karate belt colors. The color blocks were displayed near the profile picture of each ranked member. White [new beginners] to black [experts]. I haven't included any theory, but I just thought you should have the input.
EDIT: On the index page you saw the whole rating range which, I believe, helped the understanding of the colors.

mockup

download bmml source – Wireframes created with Balsamiq Mockups

1
source | link

Made a design for a gaming service some years back. The bar below indicated ranks in a modified Elo ranking system. The design scheme was inspired by karate belt colors. The color blocks were displayed near the profile picture of each ranked member. White [new beginners] to black [experts]. I haven't included any theory, but I just thought you should have the input.

mockup

download bmml source – Wireframes created with Balsamiq Mockups