The original chinese dice are small dice with the 2,3,5,6 black-colored, the 4 red colored,
and the 1 either large and red-colored, or just an impression without color.
The explanation for the red one and 4 is the following (according to everything2.com):
Once upon a time, when Emperor Hsuan-tsung of the Tang dynasty was playing dice with his concubine Yang Kuei-Fei, he needed three fours to win the game.
He threw the dice, and the first die settled immediately on a ‘four.’ Excitedly, the Emperor cheered “Four! Four!”, and both of the remaining dice, obediently, settled on ‘four‘.
Naturally, the Emperor felt rather smug about this display of imperial fiat, and a eunuch waiting on the Emperor suggested that this phenomenal fortune should be marked by something.
Thus, the Emperor decreed that in all future the ‘four’ on dice should be colored red and so it came to be.
In China red is considered to be a very auspicious colour, and the symbol of luck and good fortune.
Traditionally the ‘one’ on Chinese dice are also coloured red as the 'one' is the ace and often the highest throw in Chinese dice games.

Nowadays, however, the one is usually left blank, as seen on Mah Jongg dice, hollowed out to preserve the balance of the die.
Furthermore, the pips of the 2 are placed horizontally and not diagonally (as usual).
Modern chinese dice are still the same but often larger and both dice and pips come in many colors.

The Gambling Games Of The Chinese In America, by Stewart Culin, 1891
Chinese games with dice, by Stewart Culin, 1889

You can see more chinese dice in: MAHJONG DICE and BELANKAI SPINNERS.

[0161 x4] 4 Small bone dice with wooden box with mahjongg chips, China, 7.5 mm

[0287 x3] 'Hoo Hey How' dice, China, plastic, 19 mm.

[0288 x3] 'Hoo Hey How' dice, China, plastic, 16 mm.

[0343 x3] 'Hoo Hey How' dice, China, plastic, 19 mm.

[0376 x3] 'Hoo Hey How' dice, China, plastic, 17.5 mm.

[1213 x2] 'Hoo Hey How' dice, China, plastic, 16 mm.

[1214 x3] 'Hoo Hey How' dice, China, plastic, 16 mm.

[0043 x3] A set of 3 dice for the game "sic bo", along with its betting diagram, China, 14 mm.

[0289 x3] 3 dice, China, plastic, 15.7 mm.

[0318] Small plastic spinner from a chinese race game, 28x10 mm.

[0336] The so called "Flashing dice", rubber, 39 mm

[0346 x3] Set of 3 "Ong Su Chian" chinese chess dice where "Ong", "Su", and "Chian" are the Hokkien dialect
for 3 of the characters found on the dice, plastic, 9 mm

[0361 x6] Set of 6 bone dice in an ivory sliding box, China, 20 mm

[0677] Although only 6 of the 14 faces have chinese symbols, the die definitely falls quite often on the 8 faces.
This shape is also called a "cuboctahedron" or "truncated D6", China, plastic, 55 mm.

[0728 x4] Large foam dice, China, 63 mm

[0774 x5] Set of 5 wooden dice made for the Japanese market, China, wood, 16 mm

[0775 x12] Set of 12 plastic dice, China, 16 mm

[0855 x4] Chinese rubber gum dice also called "dice erasers", 18 mm

[0978 x4] Dice with 0-5 and 5-10 marking, China, plastic, 17 mm

[1044] A nice huge D6 with chinese scenes, not sure for what use, China, wood&ivory, 81 mm

[1045] A plastic D6 with the chinese numbers 1...6, China, 15.5 mm.

[1046 x7] Several plastic D6's, China, 15.5-18 mm.

[1047 x6] Below a set of 6 dice where only on one side dots are present.
The big one and the four are printed in red, the other numbers in black, China, 16 mm.

[1168 x6] Bone cup with 6 small dice, China, 11 mm

[1285 x2] Colourful dice, China, 15.5 mm

[1286 x2] Very small bone dice, China, 7 mm

[1287 x2] Small dice, plastic, China, 8.5 / 9 mm

[1679 x3] Dice with red 1 and 4, plastic, China, 14 mm

[1721] Black die with floriscent pips and a large 1, China, 16.7 mm