Based on the search results, "Sunny Diamond" appears primarily as a metaphor within literature—specifically referencing a description in Welcome to the Circus of Baseball by Ryan McGee, which describes a minor league ballpark. It is also frequently mentioned in the context of TikTok diamond art tutorials.

The "sunny diamond" represents the romanticized, idyllic aspect of the sport. It is a setting that evokes memories of childhood, where the green grass—or artificial turf—shimmers under the bright afternoon sun. This imagery celebrates the sport when it is stripped of its corporate "greenbacks" and reduced to its purest form: nine players on a field, spectators in the stands, and the shared experience of a game.

Here is a short essay focusing on the metaphorical interpretation of a "sunny diamond." The Sunny Diamond: Baseball’s Radiant Heart