How would you determine the approximate age of a star cluster?

how one could determine the approximate age of a star cluster? Using the Stars Colors and the and/or the positions of the stars on the H-R Diagram.|||You can determine the age of a star cluster by building an H-R diagram for the stars of the cluster and identifying the main sequence turn-off point. Large, bright stars have shorter lifespans than smaller, dimmer stars. By graphing the cluster's stars on an H-R diagram you can see that only stars up to a certain size (called turn-off point) remain in the main sequence, and that there are no main sequence stars above the turn-off point. The age of the cluster is equal to the age expectancy of a star with a mass equal to the turn-off point. All stars bigger than the turn-off point have already left the main sequence and evolved into red giants and beyond.|||was off the day they did astrophysics @ school..but obv stars in cluster all formed abt same time (good news)..but all stars in glob have diff masses (bad news)..ie they wud variously occupy diff positions on any chart of stellar evolution. Gud bet tho is 'white dwarfs'..formed from med abt solar sized stars too small to go supernova..if u cud detect these in ur cluster, by detecting movement/occultation of observable stars in the cluster, u cud work out how long it took for the cluster to form, since u know the white dwarf's orig mass limits and hence how long it took to get 2 that stage.Alt (read this on the net)..if u measure the rotrate of a sun-size/spectral type star in ur cluster, u can get its age from known solar parameters..ie sun's rotrate is slowing down @ known rate. Think u need to observe the spectrum of ur star and meas blu/red shift due to rotation.