The standard shape
For use in countries with 1:2 national flags
There is a pdf sheet showing the redesigned flag for the Commonwealth of Nations flag. The number of 'spearheads' has been reduced from 64 to 34, the globe is slightly altered to make it more 'dynamic', and the field colour is now Pantone 280, rather than 286. The device is slightly offset to the hoist. The flag is produced in two formats; the size to be used depends on the usual format within that country. The design was changed at the request of the Commonwealth Secretariat; it was adopted at the beginning of October this year.
3:5 version - the standard shape. The centreline of the emblem, the point midway between the two top spearheads, is offset towards the hoist by 1% of the flag width.
1:2 version - for use in countries with I x2 national flags. The centreline of the emblem, the point midway between the two top spearheads, is offset towards the hoist by I% of the flag width.
Colours used: Pantone 280 Pantone 116
The flag was adopted on 26 March 1976
The Commonwealth Secretariat web site includes some interesting information on the history of their flag, which it dates to 1973 but, as often understandably seems to be the case with official sources, there is no earlier symbol or flag for comparison purposes:
The Commonwealth symbol was originally designed by the Gemini News Service, London in 1972 and approved by the first Commonwealth Secretary-General, Mr Arnold Smith C.H.
In 1989 a second logo was introduced to appear on official Commonwealth Secretariat publications, and in 1999 a special commemorative logo was produced to mark the 50th Anniversary of the modern Commonwealth.
In 2000 the current Secretary-General Rt. Hon Don McKinnon, approved a new design that is now in use in place of the original designs. This design incorporates the image of the globe used in the original logo and the spears that make up the letter "C" from the 1989 design.
The radiating spears do not represent the number of countries in the Commonwealth but symbolise the many facets of Commonwealth cooperation around the world. The symbol is used on all official documentation and, sometimes in association with other specially developed logos, for the documents and logos of all Commonwealth Meetings. There is no fixed size or colour for the symbol but because of its frequent appearance on Commonwealth documentation, the black on white and gold on blue versions are commonly used.
The Commonwealth Flag consists of the Commonwealth symbol in gold on a blue background centred on a rectangle.
The flag developed from the car pennants produced for the first time at the Ottawa Commonwealth Heads of Government Meeting in 1973.
It is flown at Marlborough House, London, the headquarters of the Commonwealth Secretariat, throughout the year and for a limited period at other venues where Commonwealth Meetings are held or when other Commonwealth events/ visits are taking place for example Commonwealth Heads of Government Meetings.
The flag shown on the Commonwealth Secretariat web site uses a lighter blue and spindle-shaped spears.
Just a small bit of info I found. According to the Department of Canadian Heritage, the colors used on this flag is Pantone 287 for blue and Pantone 108 for yellow.
Also, when I looked up the design of the Commonwealth emblem, the spheres that are supposed to encirlce the globe are more like diamonds, like at here. Color information, and using the logo came from page 3 of this document.