Theory:

     In Meenakshi Ammal's house nearby, the talk went thus: "I forgot and left it in the bathroom. Kuppayi, the servant woman must have swept it out. She is very careless and ignorant."
 
     The mother, Meenakshi Ammal, consoled her little girl saying, "Let us search and find it. Don't tell Father yet. He would go into a rage if he knew that you had lost the diamond nose-stud."
 
     "What is the secret you are whispering?" asked Ramanatham.
 
     The loss of the jewel had to be admitted. Soon the whole village knew about it. The maid-servant Kuppayi was suspected by everyone to have stolen it.
 
     The police came and searched her hut, but could find nothing.
Explanation:
 
The scene now shifts from Ramayya's house to one of his neighbouring houses. A conversation related to the diamond stud was going on in Meenakshi Ammal's house. Meenakshi Ammal's daughter had lost her nose-jewel recently. She forgot and left her diamond nose-stud in the bathroom.
 
shutterstock_1874705665.jpg
Meenakshi ammal's daughter was worried as she had lost her diamond nose jewel

Though it was the daughter's fault, we see her blaming Kuppayi, their house-maid. The girl said that since Kuppayi was very careless and ignorant, she must have swept the stud out of the bathroom. The line "I forgot and left it in the bathroom. Kuppayi, the servant woman must have swept it out. She is very careless and ignorant" is important because it shows the mentality and attitude of the rich and powerful. Instead of accepting her mistake, the girl found it easier to blame it on the servant. Being a voiceless and less powerful being, the servant may not even defend herself from accusations and prying.
 
shutterstock_1148972228.jpg
Kuppayi, the servant maid

So, coming back to the story, we see Meenakshi Ammal consoling her daughter. She told the girl that they would search and find it but warned her not to tell Father as he would get furious.

Unfortunately, while the mother and the daughter were having the muffled conversation, the father entered. Ramanathan, the father, enquired about the secret conversation they were having.
 
shutterstock_1075011548.jpg
Ramanathan wanted to know about the secret

Having caught in the middle of the act, they had no choice but to confess about the loss of the diamond nose-stud. The story about the lost jewel spread quickly around the village. Everyone suspected that Kuppayi had stolen it. As a result, the police came and searched Kuppayi's hut. As expected, they found nothing in her hut.
 
shutterstock_1638771181.jpg
Police searched Kuppayi's hut but found nothing

As said earlier, we see how the powerless are easily targeted in society. It was easy to frame or suspect Kuppayi because she was poor and vulnerable. She cannot stand up against her masters and wouldn't dare to voice out her injustice. Hence, she is an easy target.
 
Meanings of difficult words:
 
S.No
Words
Meanings
1
IgnorantLacking knowledge or awareness in general
2
Console To comfort someone in the time of grief, disappointment
3
RageVery strong and uncontrolled anger
4
SuspectTo think that someone has committed a crime or done something wrong
Reference:
State Council of Educational Research and Training (2019). Term-3 English Standard-8. The Nose Jewel - C Rajagopalachari (pp. 81-85). Published by the Tamil Nadu Textbook and Educational Services Corporation.