% \usepackage[utf8]{inputenc}
% \DeclareUnicodeCharacter{2605}{\ensuremath{\star}}
%
\usepackage{fontspec}
\usepackage{newunicodechar}

\newfontfamily\symbolafont{Symbola}

% U+2605 BLACK STAR
\newunicodechar{★}{{\symbolafont ★}}

% U+2606 WHITE STAR
\newunicodechar{☆}{{\symbolafont ☆}}