Question: Are there any world-wide known Music Certification tests that you can take to use in your resume: for example, to demonstrate basic musical abilities?

I used to work in IT, where it is very common for companies like Oracle and Zend to arrange that kind of certification for a programming language or framework.

Answer: 
Generally speaking, just about every country will have music exam boards, a lot of them world wide, like ABRSM. Most have been established for many years, and the standard at any particular grade should be just that - standard.

So, on a c.v., stating Grade VI clarinet ABRSM, Trinity, LCM, AMEB etc., should give a good clue to someone reading that c.v., possibly with a little homework.

Worth a look at IMEB - which it seems is the International Music Examination Board, and, as such, would have responsibility to align all boards.
**Nothing completely world-wide, it seems.**

I'm just a hobby musician, but before joining this stack I had never heard of the type of "grades" people seem to use to measure proficiency with musical instruments. I live in **Sweden**, and it doesn't seem to be a thing here. There are entry exams you need to pass to get into music schools and academies, of course, and there is collaboration between universities to standardise some tests, but nothing as organised as what I see people discuss here, and certainly not for children.

Just to be sure, I asked my girlfriend. Her parents are both professional musicians, and she's been playing the violin in various organised contexts since she was a kid. She majored in music in high school, continued at [Folkhögskola](https://en.wikipedia.org/wiki/Folk_high_school#Sweden)(no idea how to translate..) and then spent 5 years at [university](https://en.wikipedia.org/wiki/H%C3%B6gskolan_f%C3%B6r_scen_och_musik) to become a music teacher. A teacher should know about this, if anyone. She had never heard of anything remotely like the "grades" either.

**There might be something that's fairly global, I don't know, but at least in one country it's not a thing.**