Greater magical artifacts confers immense power upon the wielder, usually more powerful and much safer than using summoned djinn to perform similar feats.
The first magical artifact to be referred to in the series, the Amulet of Samarkand contains a highly powerful entity. Like all amulets, it protects the wearer from harm. However, it is much stronger than most amulets as it is able to counteract Ramuthra.
While wearing them you are able to walk long distance with just one step. Nathanial wears them after he retrieves them from the "mercenary", who had been killed by a Pestilence.
Orginally used and created by William Gladstone, founder of the British magical empire, the Staff of Gladstone is an immensely powerful magical weapon. Bartimaeus mentioned in the The Gate of Ptolemy that it has the power of at least two marids. It can unleash destructive bolts of energy through the pentacle shape on its head.
The Ring of Solomon
Potentially the most powerful magic artifact in the Bartimaeus universe, the Ring of Solomon is a metal band that allows its user to summon thousands of spirits simultaneously, and to use the power of the greater spirit Uraziel. The ring confers near limitless power, but drains the life force of the user, as well as causing them to experience immense pain.
Lesser items are artifacts that, whilst still conveying magical power upon the user, are not as powerful or effective as those effects cast by spirits themselves.
Detonation cubes are small, cube-like devices used much like grenades. When activated they produce an explosive effect like a djinn's detonation attack.
Inferno sticks are short rods that produce a one-time effect like a spirit's inferno attack, setting the target ablaze with magical fire.
Blue orbs containing four opposing elemental spirits, elemental spheres are used much like grenades. When broken, the spirits attack to repulse one another as they escape, causing an immensely powerful explosion of elemental force to erupt from the broken sphere.