The Chinese double happiness symbol is a large Chinese character, with a heart on top which is used in red for weddings. Here is a link from where you can see how it looks like:
chineseculture.about.com
It is very different from the Chinese symbol of Longevity, which is shown at the link below;
www.living-chinese-symbols.com
chineseculture.about.com
It is very different from the Chinese symbol of Longevity, which is shown at the link below;
www.living-chinese-symbols.com