Observe the following to assess pearl quality:

• Lustre and orient;
• Nacre thickness and quality; and
• Surface texture.

1. Lustre and Orient 

A pearl is adored for its soft iridescent glow that radiates from within. Good lustre and orient fuel a pearl's enduring beauty.

Lustre

• A pearl has good lustre when there is a sharp contrast between the pearl's brightest area and the shaded area when it reflects light. This will appear as an intense "ball" on the pearl. 
• Light travels through the numerous layers of a pearl's nacre and is reflected back from within the pearl.
• The thicker the nacre, the better the lustre. The thinner the nacre, the less favourable the lustre.
• An exquisite, intensely lustrous pearl is created when numerous layers of nacre have crystallised well and are all nicely aligned.
• A pearl with low lustre is dull. Light reflection on the pearl will be hazy, chalky, or non-existent.

Orient

• A lustrous pearl, with its layers of nacre nicely aligned, allows light to be reflected from the pearl's outer surface, which in turn collides with light reflected from the pearl's inner surface.
• This light collision produces the optical effect of iridescence, which transforms the pearl into a prism.
• As our viewing angle of the pearl shifts, we indulge in spectacular flashes of colours. This is known as a pearl's orient.
• The thicker, deeper and well-formed the layers of nacre are, the more spectacular the pearl orient will be.

The more lustrous the pearl, the higher likelihood of displaying pearl orient. Lustre and orient enhance a pearl's beauty, and are also indicative of pearl quality. 

2. Pearl Surface Texture

• Pearls are nature's offsprings, they are organic.
• As pearls are organic, each and every one pearl has their own character.
• This means that every pearl may look differently from another. Just like humans, we are born special and different from another. Some may have moles, birth marks, shorter or taller in height.
• We build different characters and personalities over time in varying conditions. We experience growth when we choose to be resilient, and even so, we develop differently. Pearls are the same, organic. 

Types of Pearl Surface Textures

• In professional pearl grading terms, the varying pearl surface textures are known as blemishes, imperfections and inclusions.
• Some of these features do not affect the quality and longevity of pearls.
  
  

Bulleting or Mottling 

• A subtle plating on the pearl surface.
• This is indicative of thick and dense nacre layers. 
• It does not affect a pearl's quality. 

Bumps or Welts

• Where excess nacre has built up and formed irregular bumps on the pearl.

Circles or Ringed

• Concentric rings around the pearl. 
• Nacre welled up in the grooves of these rings. 
• Common and distinctive for Tahitian pearls. 
• Strong character feature. 

Clips 

• Small holes which affect the longevity of the pearl.
• Very common in pearls with thin nacre.

Cracks 

• This affects the longevity of pearls.

Dents or Divots

• Vary in depth.
• May match the colour of the pearl or appear to be grey or brown.

Knobs or Tips

• Short, long, pointed or bubble-shaped protrusions on one end of a baroque pearl.
• Not harmful to the pearl's longevity if not chipping or cracking.
• May add character to the pearl.

Pin Pricks

• Tiny indentations within nacre. 
• Does not affect the longevity of pearls.
• Usually colourless or matches the colour of the pearl.

Score Marks 

• Slim lines that appear "carved" on the pearl's surface nacre.
• Usually colourless.