When shall an appeal lie to the Supreme Court in civil cases?

Article 133 of the constitution provides that an appeal shall lie to the supreme court from any judgment, decree of final order in a civil proceeding of a high court only if the high court certifies [under Article 134-a]:-

(a) that the case involves a substantial question of law of general importance; and

(b) that in the opinion of the high court the said question needs to be decided by the Supreme Court.