  In this paper we construct a minimal faithful representation of the
$(2m+2)$-dimensional complex general Diamond Lie algebra,
$\mathfrak{D}_m(\mathbb{C})$, which is isomorphic to a subalgebra of the
special linear Lie algebra $\mathfrak{sl}(m+2,\mathbb{C})$. We also construct a
faithful representation of the general Diamond Lie algebra $\mathfrak{D}_m$
which is isomorphic to a subalgebra of the special symplectic Lie algebra
$\mathfrak{sp}(2m+2,\mathbb{R})$. Furthermore, we describe Leibniz algebras
with corresponding $(2m+2)$-dimensional general Diamond Lie algebra
$\mathfrak{D}_m$ and ideal generated by the squares of elements giving rise to
a faithful representation of $\mathfrak{D}_m$.
