A diamond poem, or diamante is a style of poetry

Poetry

Poetry is a form of literary art in which language is used for its aesthetic and evocative qualities in addition to, or in lieu of, its apparent meaning...

 that is made up of seven lines. The words form the shape of a diamond

Lozenge

A lozenge , often referred to as a diamond, is a form of rhombus. The definition of lozenge is not strictly fixed, and it is sometimes used simply as a synonym for rhombus. Most often, though, lozenge refers to a thin rhombus—a rhombus with acute angles of 45°...

. The form was developed by Iris Tiedt in A New Poetry Form: The Diamante (1969).

Style

A diamante poem
Diamonte poetry is a poem that makes the shape of a diamond. The poem can be used in two ways, either comparing and contrasting two different subjects, or naming synonyms and antonyms for another subject.

In the poems, the subject is named in one word in the first line. The second line consists of two adjectives describing the subject, and the third line contains three verbs ending in the suffix -ing which are related to the subject. A fourth line then has four nouns, again related to the subject, but only the first two words are related the first subject. The other two words describe the opposite subject the lines then are put in reverse, leading to and relating to either a second subject or a synonym for the first. Remember that you can't use sentences, only single words otherwise the poem won't be in a diamond shape.

Here is the order:
Noun
Adjective-Adjective
Verb-Verb-Verb
Noun-Noun/Noun-Noun
Verb-Verb-Verb
Adjective-Adjective
Noun
Remember, it will look more like
the following once you use your own words.

Here is a finished example:
Mountain
High, rocky
Flying, looking, killing
Eagle, power, fear, rabbit
Living, moving, making-noise
Deep, beautiful
Valley