All of the HTML entities you are using - ♠
(♠), ♦
(♦), ♣
(♣), and ♥
(♥) - are supposed to be black. But when I view your site's description using web browser DOM inspectors, they show as their white counterparts instead. That might be an issue with how Google parses your site's HTML and serves it back to web browsers, or it might be an issue with the web browsers themselves. Hard to say for sure, as it depends on how the HTML processor(s) define those entities between the time they are downloaded from your site and the time they reach the user's screen.
Either way, to force the black symbols, try using their Unicode codepoint values instead of their entity names, to remove any possible ambiguity in the entity name mappings:
U+2660 BLACK SPADE SUIT
hex: ♠
(♠)
dec: ♠
(♠)
U+2666 BLACK DIAMOND SUIT
hex: ♦
(♦)
dec: ♦
(♦)
U+2663 BLACK CLUB SUIT
hex: ♣
(♣)
dec: ♣
(♣)
U+2665 BLACK HEART SUIT
hex: ♥
(♥)
dec: ♥
(♥)