If you’re looking to recreate a marriage certificate as a romantic gift, templates are available online or you could use a desktop publishing package like Page Plus, Microsoft Publisher or Print Workshop. Page Plus Starter Edition is free to download online for Microsoft users or try Scribus as another freeware package if you own an Apple Mac. Desktop publishing packages will allow you to create and embellish your gift as you see fit. Print your gift on a nice matte paper or heavy card, place in a matching or home made envelope and seal with a gold sticker to add authenticity.
If you’re trying to identify a false marriage certificate, official documents are usually embossed. They will have a raised seal or perhaps a watermark that identifies the document as authentic. Most countries include these because, as stated previously, marriage certificates can be printed off the internet so false documentation is rampant. However, not all countries are so security conscious.
If you’re trying to fake a marriage certificate, I wouldn’t recommend it. This is considered fraud and if you’re caught you could be heavily fined or sent to prison.