CANNOT get c02 laser to mark certain anodized aluminum products

We are a knife manufacturer and we have had multiple knives with anodized aluminum handles for years. We've always marked the handles with our 2 c02's.

We just released 8 new knives with the same aluminum material we've always used, 4 of them are black and 4 of them are gold. The black ones etch perfect in the c02's but when we put the gold in, the c02's don't even approach marking them in anyway. I tried every combination of settings that you could think of (I'm not even kidding. I just started making stuff up trying to get this to mark).

Here's where it gets really weird. I moved the gold ones to one of our Fiber Lasers and it LIGHTLY marked it. It doesn't look good, not clear, dull color. You can kind of see it and you can feel it running your finger over but it's still not to a standard that we can sell to clients. What gets me is that Fiber lasers are not supposed to be able to mark aluminum so I'm wondering if there is some kind of coating on the gold handles. I took acetone and rubbed the handles of one hoping to remove the coating if there was one with no luck.

PLEASE HELP!!!! We don't want to use Thermark because it's inconsistent and messy. Has anyone else experienced anything like this? Please tell me someone has found a solve!