Many coin shops can do that for you.
i have a coin = 1992-1993 50p coin with certificate of authenticity =
If you doubt the authenticity of any coin, take it to a coin dealer.
If the coin is packaged, it is probably a serial number. If the coin has a serial number, it may also have a certificate of authenticity.
Coin shop or coin catalouge or the internetz
Proof coin sets always include a certificate of authenticity. Do not purchase a set that doesn't have this! You should always purchase your coins and collectibles from a reputable source. In most cases you should receive a certificate of authenticity.
The most basic thing is the weight and diameter of the coin. if you have doubts about the authenticity of the coin, take it to a coin dealer for an assessment.
Bring it to a reputable coin dealer and they will identify it and give you an opinion on its authenticity. Most coin dealers will not charge you for this service.
How much is my fathers of baseball coin collection with the certificate of authenticity
No. When cleaning the coin you cause it to lose its authenticity and value.
The one sure way to determine if a coin is real or fake is by weight. A genuine coin will have a specific weight, while a counterfeit will be too heavy or too light.
What is the value of a 2003 Alex Rodriguez gold coin
I wouldn't trust online websites to verify the authenticity. If you want to get a visa card checked, then go to your bank. If you are referring to a visa which allows you to work in a different country, then speak to the Home Office.