**8.1 Host**

Individual mussels selected for surgical nucleus implantation must be healthy and of a suitable size.

### **8.2 Donor mussel and graft tissue preparation**

The donor mussel used to get the graft tissue should have a well-developed and healthy mantle and be of the desired size. The mantle graft should be carefully selected, cleaned, cut, and trimmed, and the graft tissues should be kept in good quality water with the proper level of chemicals while the surgical procedures are being performed.

#### **8.3 Implantation**

The most important phase in the production of cultured pearls is nucleus implantation. A successful implantation technique is defined, in addition to the technician's skills, by the identification of an appropriate location for nucleus and graft insertion. More skill and patience are necessary to appropriately position and orient the graft tissue in contact with the nucleus, as well as for several nucleus implantations in a single individual.

#### **8.4 Mussel convalescence**

For the mussels to recover from the effects of narcotisation, they need regular water changes or a gentle flow through. Furthermore, the mussels should be given ample time to heal after the incision for nucleus implantation before being stocked in culture ponds.

#### **8.5 Tool maintenance**

Before usage, surgical instruments should be sharp, rust-free, and thoroughly sterilised.

#### **8.6 Temperature**

Temperature is known to influence the metabolic rate of every organism. Although higher temperatures encourage mussel growth and nacre deposition, the quality of the pearls produced suffers as a result.

#### **8.7 Quantity and quality of natural feed**

The type and amount of plankton supplied to the mussels during the culture stage is also a quality determining factor because quality and quantity of nacre secretion of the organism depends on plankton composition.

#### **8.8 Culture period**

The mussels must be nurtured for the requisite period of time to develop the proper thickness of nacre surrounding the nucleus, which contributes to the pearl's overall size, colour, and shine. The culture period might last anywhere from 12 to 18 months, depending on the type of nucleus used and implantation employed.

The raw pearl obtained from the implanted freshwater mussels are inapt be to directly used as a jewel. The pearls are value added after harvesting in order to improve quality and maintain consistency. They are subjected to a variety of procedures, including cleaning, bleaching, dyeing, or both. For cleaning or bleaching, hydrogen peroxide, ether solvents, water, and alcohol are used in varied amounts depending on the need. Ultra sonication, for example, is a physical treatment process that removes any clinging contaminants. Other chemicals, such as EDTA, sodium hypochlorite (NaOCl), and calcium hypochlorite (bleaching powder), can help remove adherent particles by chelating, oxidising, or bleaching them. Pearls have been demonstrated to shine when treated with EDTA, NaOCl, chlorine, and hydrogen peroxide [82].

Studies have shown that the colour of cultured pearl can be enhanced using radiation and chemical treatment. 48 h exposure to 5.423% 10−2 M rad of gamma radiation, treatment in 1.2% eosin solution for 24 h, 20% iodine solution for 48 h and 0.2% silver nitrate solution for 24 h result in distinct changes in the colour of pearl from white to black, pink, yellow and metallic brown or black, respectively. It was also observed that the coloration caused by gamma radiation and silver nitrate was everlasting [82].
