S.C. Code Ann. § 20-1-260

The probate judge or any other officer authorized by law to issue marriage licenses shall not issue any license to any applicant under the age of eighteen years until he has filed a birth certificate, or a hospital or baptismal certificate which has been issued and dated within one year after birth, or a certified copy thereof, showing that he is of lawful age, which shall be filed in the records of his office with the application for such license. Provided, when an original birth, baptismal or hospital certificate is presented a copy of it shall be made and the original returned to the applicant. If the applicant shall certify in writing to the probate judge or such officer that he, after diligent effort, is unable to obtain a birth certificate or a hospital or baptismal certificate, the applicant shall then be required to have his parents, legal guardian or person with whom he resides execute an affidavit before any person authorized by law to administer an oath and under seal, which affidavit shall contain such information as will establish the age of the applicant. Provided, further, that upon the request of the applicant, any original birth, baptismal or hospital certificate presently on file with the court may be copied and the original returned to the applicant. Persons applying for marriage licenses in lieu of furnishing birth certificates or hospital or baptismal certificates may present the following: military service identification card; selective service identification card; passports and visas.