Tucked behind a small gem museum (which itself is not thoroughly impressive, but it was interesting to see the rocks that many gems come from) and a linked gem store is the cozy Gem Cafe. The cafe includes a few bar-height seats in two covered areas and several cushioned seats in the beautiful atrium area of the traditional house. The atrium area has a water wall on one end, and plenty of greenery and bamboo keep the area cool(-ish) and shaded in the heat of the day (as do the upper floors around it). The cafe has wonderful jazzy music playing, which adds to the relaxation. (I recognized actual jazz as well as jazz versions of rock/pop music // also soft rock and blues mixed in.)
Glasses of wine seemed to range from VND 125000-165000, but there was a special with a glass for VND 90000 when I visited and it was an enjoyable wine.
This is simply a nice place to relax, especially in the heat of the day. I feel like the main seating area would remain pretty but would be unusable when it is raining -- since there is very limited seating under a roof -- but I do no’t know for sure and it is otherwise excellent.
For what it is worth, there is also a gem sculptures museum upstairs that is the only part of the museum that requires a ticket.. I did not try it, though.