Can a gyn tell by looking i have herpes ?

If you have lesions: If you have the typical lesions(blisters)most of the time one can and can be confirmed by taking a culture.

Herpes: 90% of people who have herpes two (genital herpes) do not have outbreaks but are still contagious. So, no. Only through a blood test will a physician be able to fully and with validity be able to diagnose whether you have been infected with herpes. Now, if you have a sore or lesion or outbreak many physicians are very experienced to diagnose this by visual inspection. But, the blood test must.