The symbolism of carnations varies. Broadly speaking, carnations symbolise admiration, affection, dignity, health, joy, love and strength. There are some less joyful meanings - like disappointment and misfortune - but we like to focus on the positives!
Certain colours can have a specific meaning. For example, pink carnations can mean a mother's love; light red is the carnation you give for someone you admire; if someone your love for someone is beyond imagining, you could give a mauve carnation - it symbolises dreams of fantasy; while a yellow carnation is a good colour to give if you need to let someone down gently, as it means rejection.