There are considerable colour variations with teak. Naturally dark teak is
generally more dense than lighter coloured teak.
Different regions of Myanmar (Burma) yield teak of differing colours; dry
climate grown teak verses wet climate grown teak.
Some teak has what is called 'black streak' and this is found more often in
some regions of Myanmar than others.

Some fresh sawn teak comes off the mill greenish and stinking; the Thais
call this 'Khee mai' which translates as "wood that smells like chicken
sh*t."
Sun and air causes this bad smelling green teak to oxidize and turn that
attractive teak brown colour you are used to seeing.
All my fresh sawn teak sits in the sun for 24 hours to turn colour prior to
shipping.

Your question concerned having a dark teak. I would sand the surface first
and see what is underneath the surface, it may not be that dark.

Golden teak is a characteristic of teak that naturally occurs in a few
specific regions/altitudes of Myanmar. Mid 'brown colour' teak is the norm.

Matching 'teak' on an existing boat can be problematic because the 'teak'
may not be teak at all, but something passed off as 'teak' such as
'Phillipine mahogany' is passed off as true mahogany.......which it is not.
There is also the plantation teak that can take on lighter/darker colour
depending on the fertilizer and general growing conditions.

Western red cedar is somewhat similar........ you can fine light coloured
red cedar and very dark red cedar. The dark is generally regarded as
superior.

Personally, I set aside my dense, dark teak to keep for myself.

........Ken / Island Teak (Canada)