10/29/2013 at 04:00 PM EDT
birthday party continues.
On Monday, the singer celebrated her big day – and engagement to rapper/producer, Future
– by hosting an event at the Moët Rosé Lounge in Houston.
While the celebration was in honor of the "Body Party" singer turning 28, all eyes were on her massive engagement ring.
"She talked about the engagement – she's super sweet and you could see that she was excited and happy about it all," an onlooker tells PEOPLE. "She gushed about Future and just kept saying that it was such a great birthday surprise."
During the event, Ciara posed for photos with fans, letting them sit in the VIP area for photo pops.
"A good 100 people came into the VIP area to take photos and wish her and Future the best," the source adds.