Deep blue shading to green above, the tones of sea at night outlined in smooth, bold sweeps and strokes of form.  She - there can be no doubt of gender - she's slim without being waifish; pleasantly rounded at keel and haunch without a hint of spare flesh, the whole sheened with a hint of moisture that catches and reflects just enough light to accentuate her shape.  Indeed, something gleaned from diet or nature has collected into two lines of tiny, faint-glowing spots that trail from just beneath each nostril, back along the jaw and neck before plunging enticingly along the strong arch of her throat to meet at the base; there they fade, only to return about the curves of hip and hock.
That she's born of the ocean is evident; the lines of her body are smooth and streamlined, her wings agile and strong but lacking the outswept pinions necessary for flight.  Instead she sports a proud fin that sweeps from each back to her haunches, dipping low along the early curves of that sinuous appendage before flaring once, twice and thrice into a broad ripple of diaphanous membrane that apes the flukes of more commonplace sea-life.  Even in air these swish and drift in slow sympathy of her movements, the whole giving an appearance rather like a dancer trailing ribbons.
No horns mar the elegance of her head: An almost horse-like muzzle tipped with nostrils that can flare wide to sample a scent, or close tightly to hold one at bay.  Her teeth, should they be exposed, are needle-pointed and manifold, serving both to snatch passing prey and sift smaller motes from the water.  There's what appears to be a small barnacle nestled at the corner of her jaw just below the left of her twin ear-holes, its shape picked out with miniature pearls and chased with silver.  Whether this is a living creature or mere affectation is unclear.