Final answer:
The color described as a greenish blue or bluish green is turquoise, which is similar to the hue of the gemstone and is associated with the vibrant look of tropical waters.
Step-by-step explanation:
The color that is often described as either a greenish blue or bluish green is turquoise. This color is akin to the hue of the turquoise gemstone, which has a unique mix of blue and a slight amount of green. This color is often associated with the clear tropical ocean as it gives off a soothing and vibrant feel. It is not as dark as teal, which tends to lean more towards green and has a darker, more muted tone compared to turquoise. The color indigo is a deep blue with a violet tint, and sapphire is a bright and vivid blue, without the greenish mix that defines turquoise.