They found the diamond-bearing Kimberlite pipes in Canada by retracing the path of the glaciers from the glacial deposits where the stray/transported diamonds were found.
Nothing unusual for geologists working with glacial deposits.
Same situation ocurred in Ohio, there is no reason to invoke a comet to explain it.
What a party pooper.
Climate change is a win/win for Ohio. If it gets warm Dayton could become beach front property. If it gets cold and the glaciers come back there’s diamonds for everyone.