From the 1915 publication 'The Training and Employment of Grenadiers'.
WEIGHT of grenade complete 1 lb. 6ozs.
WEIGHT of ammonal 5 1/2 ozs.
DESCRIPTION. (See Plate 25.)
The body is a cast-iron sphere 3" in diameter, filled with ammonal, and closed by a screwed steel plug 1 3/8" diam. This plug carries a copper tube to take the detonator into the centre of the grenade. There are two holes in the top of the plug to take a key for the plug which is screwed down flush. Two copper wires, for tying down the fuze, are attached to a small stud on the plug. Lighter, fuze and detonator; as for No. 8 and 9 Grenades, or Brock Lighter.
Instructions for throwing. The precautions' to be taken are also the same as for Nos. 8 and 9 with the addition of waxing round the plug.
Sectioned image of the ball grenade from the same document.
From the 1918 book 'Explanatory List of Service Markings to be found on ammunition and ammunition packages in use with the Field Armies'.
Grenades
Stencilling
Red ring = when filled.
Pink band = Ammonal and Alumatol fillings.
Green band = Amatol filling.
1.5 inch red square on grenades filled K.J." mixture.
In the cases of grenades with other fillings, the nature of the explosive is stencilled on the lid of box only.
So as BMG50 stated, it should have a red and a pink band. The first for its HE fill. The second to denote the ammonal filling.