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To get the Diamond Trophy you need to collect a total of 15 Gold Crown or Sugar Star from the episode. When you pass a new level on the first attempt, the level crown will turn to gold, that is, the gold crown. If you fail to pass the level on the first try, you will miss the Gold Crown, but if you can collect the Sugar Star at that level later, it will count for the Diamond Trophy.
According to your screenshot, Level 217 had a Gold Crown so it counted for the Diamond Trophy, but if you get the Sugar Star again at the level where the Gold Crown already, it will not count again.
At Golden Crown levels, Sugar star will not be counted.
From (216 to 230) episodes you will have to collect 4 more Sugar Stars then you will get Diamond Trophy and the levels are respectively 225, 226, 227 and 228.
I hope this has become more clearer to you😊