In any event her symbol should be a Pink Rose. A mixture of White for Purity of Faith, Motherhood, the French Royal colour, and Red for her Martyrdom.
Prayer to Saint Marie-Antoinette
Saint Marie-Antoinette, martyred Queen, despised by the people whom you loved, you coupled your sufferings to that of Jesus our Lord and Savior. You remained strong in hope, when you could have disparaged. When presented with the instrument of your death you remained firm in your faith and never doubted the resurrection and the Kingship of Christ.
You, Martyred Queen of France, who is in the beatific presence, pray for us in the hour of our greatest need.
Vive la Reine!
Vive le Roy!