The Q is a measure of the damping in the tuned circuit. That almost all comes from the coil, and it is easier to measure.
There are various ways to measure it. You can measure with an oscilloscope how fast the waveform decays. Q about twice the inverse of the decay per cycle, so if the waveform decays to 90% in one cycle, it decays by 10%, and the Q is about 2*1/0.1 = 20
You can also work out the impedance at resonance. That will be about Q * ωL and for your circuit ωL = 2*π*100e6*100e-9 = 63.
So if you have a resonant circuit, and you find that a 1kΩ resistor in parallel causes the amplitude to halve, the impedance of the resonant circuit must be around 1kΩ, so the Q is about 1000/63 = 16
In my experience, you won't get a Q more than 20 at 100 MHz without a lot of effort.