The only relevant Oracle certification that I am aware of is:
1Z0-574 -- Oracle IT Architecture Release 3 Essentials
The 'Essentials' certifications tend to be just that. It's not going to go into great depth or provide 'proof' that you are an expert Data Architect. That said, studying for the exam may well make you better at that skill, which is really the point of becoming certified.
That *is* a certification specific to data architects. My caution to you was simply that the 'Essentials' exams tend to focus on fundamentals rather than advanced topics. I am not aware of an advanced certification specific to a Data Architect. Frankly I consider that to be a topics that would be extremely difficult to create an advanced test for. Testing for someone's ability to design doesn't mesh well with multiple-choice exams.