  It is found that Gaia DR3 binary stars selected with stringent requirements
on astrometric measurements and radial velocities naturally satisfy Newtonian
dynamics without hidden close companions when projected separation $s \lesssim
2$ kau, showing that pure binaries can be selected. It is then found that pure
binaries selected with the same criteria show a systematic deviation from the
Newtonian expectation when $s \gtrsim 2$ kau. When both proper motions and
parallaxes are required to have precision better than 0.005 and radial
velocities better than 0.2, I obtain 2,463 statistically pure binaries within a
`clean' $G$-band absolute magnitude range. From this sample, I obtain an
observed to Newtonian predicted kinematic acceleration ratio of
$\gamma_g=g_{\rm{obs}}/g_{\rm{pred}}=1.49^{+0.21}_{-0.19}$ for acceleration
$\lesssim 10^{-10}$ m s$^{-2}$, in excellent agreement with $1.49\pm 0.07$ for
a much larger general sample with the amount of hidden close companions
self-calibrated. I also investigate the radial profile of stacked sky-projected
relative velocities without a deprojection to the 3D space. The observed
profile matches the Newtonian predicted profile for $s \lesssim 2$ kau without
any free parameters but shows a clear deviation at a larger separation with a
significance of $\approx 5.0\sigma$. The projected velocity boost factor for
$s\gtrsim 5$ kau is measured to be $\gamma_{v_p} = 1.20\pm 0.06$ (stat) $\pm
0.05$ (sys) matching $\sqrt{\gamma_g}$. Finally, for a small sample of 40
binaries with exceptionally precise radial velocities (fractional error
$<0.005$) the directly measured relative velocities in the 3D space also show a
boost at larger separations. These results robustly confirm the recently
reported gravitational anomaly at low acceleration for a general sample.
