This site has a very detailed and authoritative discussion of the sinking of the Titanic:
http://users.senet.com.au/~gittins/index.html
Going to Terminology and then to Distress Signals you find:
**"In 1912 the internationally recognised distress signals were as set out below. The only one employed by Titanic was the third among the night signals. Fourth Officer Boxhall told the British enquiry that he fired socket signals, which were rather like mortar shells, rather than rockets as commonly understood. All were white in colour. Two little Titanic mysteries are why 65 minutes elapsed after the collision before they were fired and why the huge foghorn was not tried.
It should be noted that these lists do not mean that there was an order of preference. Each signal was equally valid. It was also provided that a doubtful signal was to be taken as a distress signal
Signals of Distress.
When a vessel is in distress and requires assistance from other vessels or the shore, the following shall be the signals to be used by her, either together or separately:
By Day.
A gun or other explosive signal fired at intervals of about a minute.
The international code of distress indicated by NC.
The distant signal, consisting of a square flag, having either above or below it a ball or anything resembling a ball.
The distant signal, consisting of a cone, point upward, having either above it or below it, a ball or anything resembling a ball.
A continuous sounding with any fog-signal apparatus.
By Night.
A gun or other explosive signal fired at intervals of about a minute.
Flames on the vessel (as from a burning tar barrel, oil barrel, etc).
Rockets or shells, throwing stars of any colour or description, (my emphasis) used one at a time at short intervals.
A continuous sounding with any fog-signal apparatus."**
So the colour isn’t important - it’s the timing.
If you’re interested in the Titanic, it’s well worth reading through the whole site.