In my opinion, it's better to keep expensive cologne in your hand luggage. This is for a few reasons. Firstly, you're less likely to have to deal with an 'exploding cologne bottle' situation if you have your cologne with you and can keep an eye on it. Baggage handlers have to work quickly and accidents can happen with checked luggage. Secondly, there's always a small risk associated with anything in your checked luggage. Bags get lost, and sometimes items can get stolen too. If your cologne is important to you, keep it with you in your checked luggage just in case.