K(Y1-xYbx)3F10 (x = 0-1) solid-solution nanocrystals embedded glass ceramics were fabricated via glass self-crystallization. Using Eu(3+) as a structural probe, the partition of lanthanide activators into the K(Y1-xYbx)3F10 lattice was evidenced. As a consequence, color-tunable upconversion luminescence from green to red was easily realized by modifying Yb(3+) content in the Er(3+)-doped nano-glass-ceramics.