Konstantinos Doukas, sebastos, last third 12th century-early 13th century. Seal (Lead, 30 mm, 23.32 g, 6 h). Θ / ΓЄ/ⲰP-ΓH/OC Saint George on horseback to right, nimbate, holding spear in his right hand. Rev. CΦPAΓICMA / ΔOVKA CЄRACT૪ / KⲰNCTANTIN૪ / ONΠЄP AΘΛHTA / ЄK ΠACHC RΛA/RHC PVOV ("Seal of Konstantinos Doukas, sebastos - Champion, save him from all harm") in six lines. Jordanov, Corpus II 201; Wassiliou-Seibt, Corpus 2722. An impressive seal with an extremely rare image of Saint George on horseback. Some marks and scratches, otherwise, very fine.
As Cheynet remarks in his comment on the Zacos seal, the name Konstantinos is common in the Doukas family and identifying this seal's owner with any certainty is therefore problematic. However, Cheynet proposes as a likely candidate the Konstantinos Doukas who was Konstantinos Laskaris's rival for the throne in April 1204, after Alexios V' flight from Constantinopolis and just before the Crusaders captured the city.