Generally speaking, for personal use, I think Diamond Shoes are generally best used on Diamond cards, starting from around real-life Playoffs time. But I could see an argument for putting it on an Amethyst or Diamond you have now, even though it won't be an endgame card, because you will play the card so much between now and when you stop playing it.
I got lucky by drawing the Diamond Air Jordan XXXI Low that gives +9 to Open 3, Open Mid, Accel, Hands, and Pass Accuracy. Amethyst Artest wouldn't waste a point of those boosts and I'm pretty sure he could be useful at least as a bench defensive specialist for most of the cycle. But I'll wait...
I could see same rationale for your using your shoe on Bob Love. But your shoe is kind of tricky. On one hand, it's probably best to use it on a Center, but you're going to find it hard to put it on a Center that will be endgame quality, even with the shoe. And those that are endgame cards will waste a lot of those boosts.
What might be the best candidate for the shoe is an endgame-quality wing player that you want to play as a Stretch 4. Think of something like 2K17's Diamond Pippen. Or the Diamond James Worthy.
But if you want to try to convert the value to MT, then I think I would wait for some packable Amethyst Center that is a popular player and which could use at least most of the boosts. Last year's Amethyst Yao would be an ideal candidate for the shoe:
http://2kmtcentral.com/17/players/20288/ming-yao