The flag of Brazil has a green field with a large yellow diamond in the center, inside of which is a blue circle containing 27 small white, five-pointed stars arranged in the pattern of the night sky as it appeared on November 15, 1889. The aspect ratio of the flag is 7:10.

Colors and their respective color codes:

1. Green (field): Pantone 355 C, HEX #009C3B, RGB (0, 156, 59)
2. Yellow (diamond): Pantone 116 C, HEX #FFCC29, RGB (255, 204, 41)
3. Blue (circle): Pantone 280 C, HEX #002776, RGB (0, 39, 118)
4. White (stars): Pantone White, HEX #FFFFFF, RGB (255, 255, 255)

Geometric properties and measurements:

1. The green field covers the entire flag.
2. The yellow diamond's vertices touch the middle points of each side of the flag.
3. The blue circle is centered within the yellow diamond and has a diameter equal to 3/7 of the flag's height.
4. The 27 white stars represent the 26 states of Brazil and the Federal District. They are arranged in nine constellations as they appeared in the sky over Rio de Janeiro on November 15, 1889, at 8:30 am.