Since coming to the Diocese Bishop Tomlinson has considered the adoption by the Diocese of a Coat of Arms.  Apparently Bishop Daly commissioned a Coat of Arms for the Diocese in 1979, but it was never used.  With the help of a number of people a suitable Coat of Arms for the Diocese was devised.

The arms of the Diocese of Sandhurst are blazoned:

• Quarterly, per saltire or and azure on the former in fess two roses gules, in chief an estoile (or eight (8) pointed star) and in base a representation of the Paderborn Cross argent.
• The gold of the field represents the goldfields which is located within the diocese and the blue represents the Virgin Mary, Mother of God.
• The star and the two roses have their origin in an earlier design proposed for the arms of the diocese in 1979. This proposal does not appear to have been put into use, its existence is little known in the diocese and its original symbolism is not known at all.
• The Paderborn Cross which is represented in base was discovered at Paderborn in Germany which was the place of origin of Dr Henry Backhaus, the pioneer priest of the Bendigo Goldfields and the architect of the financial security of the diocese and of the cathedral.

The diocesan arms are displayed alone or impaled with those of the Bishop.
 
The diocesan arms were designed by Fr. Guy Selvester and Richard d’Apice AM KCSG and illustrated by Sandy Turnbull both of the Australian Heraldry Society.