User blog comment:B214/General Discussion/@comment-27083298-20160929165937/@comment-29963364-20160930031248

Take a look at this picture of Sairaorg.

http://vignette2.wikia.nocookie.net/highschooldxd/images/5/58/418px-High_school_dxd_v10_085.jpg/revision/latest?cb=20120526151140

See that flower symbol on the collar of his shirt?

And remember that, in vol. 21, Magdaran Bael (Sairaorg's little half-brother) said that the purple flowers that grow in the Bael territory are involved in the Bael Clan's crest.

So I believe that the Bael Clan Symbol is that flower symbol on Sairaorg's shirt, but collored purple.