The Format (or layout) of a Bank Guarantee will be governed by the SWIFT Message Type database fields.
One thing is for sure, a genuine Bank Guarantee will not look like a swimming certificate and will certainly not contain fancy wax seals!
It will generally resemble a normal bank letter. It will state the basic information at the top, i.e. Issuer, Date of Issue,Expiry, Beneficiary etc.
Some Bank Guarantees are sent in original form (by letter) and also by SWIFT.