Argentina offers a certificate which is internationally acknowledged: CELU, Certificate of Spanish: Language and Use.
CELU is a proficiency test of Spanish as a foreign language. It can be taken by any foreigner whose mother tongue is not Spanish and who wants to prove his or her ability to use Spanish as a second language in working and academic contexts. The CELU examination is officially acknowledged by the Ministry of Education and by the Ministry of Foreign Affairs and Worship of Argentina.
For more information, click here.