You call a Construct you control.

First, you must place your Arcane Mark on the Construct. Then you cast this spell, which magically and invisibly inscribes the name of the Construct on a sapphire worth at least 1,000 gp. For constructs such as golems that are immune to magic, the value of the specially inscribed sapphire must be at least 5,000 gp. Thereafter, you can Summon the Construct by speaking a special word (set by you when the spell is cast) and crushing the gem. The Construct appears. Only you can use the gem in this way.

If the Construct is no longer under your control or destroyed, the spell fails, but you know roughly where the Construct or its remains are located.

The inscription on the gem is invisible. It is also unreadable, except by means of a read magic spell, to anyone but you.

The Construct can be summoned from another plane, but only if no other Creature has claimed ownership of it.