Tokays grow to a maximum snout-vent length (SVL) of 185 mm and reach total lengths (tL) of 365 mm. Fully grown females are smaller than males. The entire upper face is covered with small scales and 12-14 rows of tubercles on the back. Mature males have an angular row of 10-24 preanal pores. Females have an angular row of enlarged preanal scales instead in which the pores are inactive and therefore weakly expressed. Fingers and toes are much widened and end in claws on all but the innermost digits, as is typical of this genus. The subdigital lamellae are entire (undivided), which is also characteristic of this genus.
The dorsal ground colour varies with the individual and the origin of a specimen, ranging from light, medium, greenish, bluish and dark grey to light blue. The area between the nape of the neck and the base of the tail is usually marked with seven bands of white, dirty white, greyish, bluish or greenish white spots. The interspaces between these fragmented bands are patterned with yellowish, orange, blood red or brownish spots, but these markings may be partly or completely absent in some individuals. The top of the head is usually spotted with red, with the spots often being arranged to form a “Y” in its centre. The mucous membrane of the mouth is blackish. The eyes are usually the colour of amber around the slit-shaped pupil, but may also be reddish brown or brown. The lower side can be whitish, beige, dirty, bluish or greenish white, with a speckling of yellowish, orange, red or reddish brown all over or in parts.
Hatchlings are dark grey to blackish above, with a contrasting white pattern of spots arranged in bands on the body and white bands on the tail. The red spotted patterns become more prominent as the juveniles grow older.
Uniformly coloured individuals have also become known, being light blue (GROSSMANN 1987), white, dirty white, yellow, beige, light brown, medium brown or black (GROSSMANN 2004). Moreover, certain colour morphs have surfaced recently, with these Tokays not being unique aberrations. These include, e.g., the so-called Calico Tokay, entirely black specimens, and green Tokays with a blue head. It is as yet unknown where these morphs of the Tokay come from.
Like all geckos, Tokays shed the uppermost layer of their skin (the epidermis) at regular intervals in a process that is called ecdysis or, simply, mould. The first mould occurs shortly after hatching. The intervals between moulds become longer as the geckos grow and age and are therefore longest in old specimens. Tokays approaching a mould are notable for their showing a milky, obscure colour pattern. This is caused by the uppermost layer of the skin starting to detach from the newly formed epidermis beneath. The old skin eventually begins to peel off from the tip of the snout, usually in large patches. The geckos actively support this process by pulling these pieces off with the mouth. They usually eat the exuvia (shed epidermis) without leaving anything behind. Old skin thus forms the first food for every hatchling Tokay.