How do i prevent natural nails from being visible through builder gel?

I want to do elegant, thin nails but every time i do builder gel the tips of my natural nails are visible through the gel (most visible through the light and outside, appearing whiteish) and i have to apply it thicker when i do them to prevent that. This happens mostly with white gels and some nude color gels. I file them correctly and build the apex correctly. Am i missing something? I use a transparent coat of rubber base underneath before applying builder gel. Do i need a nude colored rubber base or?