How much is a purple rupee worth in Zelda?

Could you please clarify for me, as I'm a bit confused - are we talking about the video game franchise "The Legend of Zelda" here? And if so, I'm not aware of any specific currency within the games being called a "purple rupee." Could you perhaps be referring to a different item or currency within the game that has a purple hue? In any case, could you provide more context or details about what you mean by "purple rupee" in the context of "The Legend of Zelda"? It would help me better understand your question and provide an accurate answer.