Found this and thought it was helpful:

Egg White Verses Semen


It can be difficult to distinguish between the two. Here is how to tell apart...

1. Egg White will ball up and sink in Water and will remain stretchy when retrieved. Semen will float and dissolve.
2. Egg White will stretch repeatedly. Semen may stretch once or twice, but not for much longer.
3. Egg White is very shiny, and clear or slightly opaque. Semen is less shiny and creamy.
4. Egg White will stretch to form several thin strands. Semen will stretch with just one strand.

Also Semen will only stretch once or twice on your fingers, where as CF will continue to stretch. And semen will begin to get very tacky as well.