From the Royal Caribbean Web Site...
For Diamond members sailing on Freedom and Oasis class ships, the Diamond lounge will continue to be open during regular hours with the Diamond lounge concierge at your service. If there are any changes to the time or location, the Loyalty Ambassador will announce these changes in the Welcome letter to be placed in your stateroom on the first day of the cruise.
We now offer either the Diamond Lounge or a Diamond Event on every ship in our fleet. On ships with a Concierge Lounge, it will be limited to Diamond Plus and Suite guests (excluding Junior Suites).