Help > Authoring > Equations > Customizing the Equation Editor > Greek markup > Bold Greek
  
Bold Greek
The following are always placed inside <bg> (bold Greek) tags:
D \boldDelta
F \boldPhi
G \boldGamma
L \boldLambda
P \boldPi
Q \boldTheta
S \boldSigma
U \boldUpsilon
W \boldOmega
X \boldXi
Y \boldPsi